No, you just misread it. Read it again:
Hebrews 9:26 KJV - For then must he often have suffered since the foundation of the world: but now once in the end of the world hath he appeared to put away sin by the sacrifice of himself.
Hebrews 9:27 KJV - And as it is appointed unto men once to die, but after this the judgment:
Hebrews 9:28 KJV - So Christ was once offered to bear the sins of many; and unto them that look for him shall he appear the second time without sin unto salvation.
The "once" ["once offered to bear sins"] in the "end of the world" is specifically speaking about the "sacrifice" of Jesus Christ, which took place approx 2,000 years ago [aka, two "days" with the LORD ago.] Jesus Christ appeared at the
First Advent, after 4,000 Years [aka 4 "days" with the LORD]. Thus He appeared at the end of this world's week, being in the final portion of the Great Week [7 Days, 6,000 Years + 1,000 Years].
Yes, I agree with you that
Jesus appeared once 2000 years ago to become our sacrifice to forgive our sins.
This was Jesus' first bodily appearance on earth.
Notice that the last portion of Hebrews 9:28, reveals that we [Christians] are to "look for Him" to "appear the second time" "without sin" "unto salvation". The Second Advent is for the collection of the Saints/Christians. Thus they after that point are "ever with" the LORD. They [Christians] do not need to "look for him" a third time, since they are ever "with" Him after that. hence, "Titus 2:13 KJV - Looking for that blessed hope, and the glorious appearing of the great God and our Saviour Jesus Christ;"
Jesus' second appearance/advent will be for the gathering of the saints and it will also be for the gathering of the evildoers. Both of these events will occur when Jesus returns to earth for His second/final appearance at the end of time.
Matthew 13:40-42
Therefore as the tares are gathered and burned in the fire, so it will be at the end of this age. 41 The Son of Man will send out His angels, and they will gather out of His kingdom all things that offend, and those who practice lawlessness, 42 and will cast them into the furnace of fire. There will be wailing and gnashing of teeth.
Matthew 24:30-32
Then the sign of the Son of Man will appear in heaven, and then all the tribes of the earth will mourn, and they will see the Son of Man coming on the clouds of heaven with power and great glory. 31 And He will send His angels with a great sound of a trumpet, and they will gather together His elect from the four winds, from one end of heaven to the other.
1 Thessalonians 4:16-18
For the Lord Himself will descend from heaven with a shout, with the voice of an archangel, and with the trumpet of God. And the dead in Christ will rise first. 17 Then we who are alive and remain shall be caught up together with them in the clouds to meet the Lord in the air. And thus we shall always be with the Lord. 18 Therefore comfort one another with these words.
Please note that the angels accompany Jesus when He returns to earth at the time of His second/final appearance and it is the angels who gather up His followers in the air to meet Jesus in the clouds.
Hebrews 10:27, reveals others looking for something else, which does not take place until after the 1,000 years in fulness, hence the 'third' Advent:
Hebrews 10:27 KJV - But a certain fearful looking for of judgment and fiery indignation, which shall devour the adversaries.
Hebrews 9:28
so Christ was offered once [His first appearance on earth] to bear the sins of many. To those who eagerly wait for Him He will appear a second time [His final appearance on earth], apart from sin, for salvation.
There is no third advent/coming/appearance of Jesus. When Jesus returns to earth for His second/final appearance,
His followers will be saved from the wrath of God. Jesus will command His angels to gather His saints together in the air to meet Him in the clouds on top of Mt. Olivet.
Zechariah 14:4, Acts 1:9-12https://www.biblegateway.com/passage/?search=Zechariah+14:4&version=NKJV
Jude 1:14-15
Now Enoch, the seventh from Adam, prophesied about these men also, saying, “Behold,
the Lord comes with ten thousands of His saints, 15 to execute judgment on all,
to convict all who are ungodly among them of all their ungodly deeds which they have committed in an ungodly way, and of all the harsh things which ungodly sinners have spoken against Him.
Please note that both the godly and the ungodly will all be together on earth when Jesus and His saints return to earth for His second/final appearance. All people, both godly and ungodly will then be taken by the angels to the great white throne judgment/sheep and goat judgment/etc.
Hebrews 9:28
so Christ was offered once to bear the sins of many [2000 years ago]. To those who eagerly wait for Him He will appear a second time, apart from sin, for salvation.
Christ appeared on earth once so far and that was 2000 years ago. That was His first appearance. He will appear on earth a second time to gather His followers together with Him so that they can be forever with Him. And then, the judgment of all people commences and the earth is destroyed by fire.
https://www.biblegateway.com/passage/?search=2 Peter+3:7&version=NKJV
2 Peter 3:7
But the heavens and the earth which are now preserved by the same word, are reserved for fire until the day of judgment and perdition of ungodly men.
Revelation 21:1
Now I saw a new heaven and a new earth, for the first heaven and the first earth had passed away. Also there was no more sea.
2 Peter 3:13
Nevertheless we, according to His promise,
look for new heavens and a new earth in which righteousness dwells.
John 5:26-30
For as the Father has life in Himself, so He has granted the Son to have life in Himself, 27 and has given Him authority to execute judgment also, because He is the Son of Man. 28
Do not marvel at this; for the hour is coming in which all who are in the graves will hear His voice 29 and come forth—those who have done good, to the resurrection of life, and those who have done evil, to the resurrection of condemnation. 30 I can of Myself do nothing. As I hear, I judge; and My judgment is righteous, because I do not seek My own will but the will of the Father who sent Me.
There is only one general judgment of both the good people and the evil people and it occurs when Jesus returns to earth for His second/final appearance.
The
hour is coming in which Jesus gathers all people for the final judgment of all the good people and of all the evil people.
One hour only is coming for the judgment of both the good people/sheep and the evil people/goats. There are not two separate judgments for the righteous and the unrighteous.