There are people who believe that the Septuagint Greek translation was quoted in the epistle to the Hebrews.

They believe that some are direct quotations, but that others are "close" quotations. 

For example, that of Martin Karrer, in:  The Epistle to the Hebrews and the Septuagint

"So our author indicates a greater poetic license where he abstains from introductory formulae.

The dividing line between quotations and allusions becomes blurred.

Hence one should modestly weigh such quotations"

Which is significantly different than simply believing that what is written in Hebrews is exactly what the Holy Ghost inspired to be written.

Many places in the Bible, the LORD repeats things, at different times.

Sometimes the words are the same, and sometimes they are similar.

That doesn't mean that the LORD sometimes correctly quoted himself, but other times "misquoted himself".

No, it simply means, he said things again, sometimes with the same words, and sometimes with similar words.

Jesus repeated things in the gospels, sometimes exactly the same way, sometimes similarly.

But, since all scripture is given by inspiration of God, the similar phrases are not "misquoting" the previous phrases.

A similar, repeated phrase, is as much the inspired word of God as the first phrase.

Like, not hiding a candle, but putting it on a candlestick, is mentioned early in Jesus' ministry, in the sermon on

            the mount in Matthew 5:15, then later in Luke 8:16, and then, again, in Luke 11:33.

So, if the Holy Ghost had something written in the epistle to the Hebrews, that was very much like

            something written in the old testament, it wasn't an "almost-quote", but simply another inspired verse, this time in the new testament.