It is the same class of servant, all of which are not ready, with differing degrees of iniquity/unworthiness, and thus differing degree of punishment. As said, the only place mentioned in this parable is with the lost. You are using the difference in the degree of punishment in order to read a temporary place of punishment that would make them fit for Heaven, but which is simply not in the text. Give it up.
For whom the Lord loveth he chasteneth, and scourgeth every son whom he receiveth.
And which reformable or purifying experience (which 1Co 3 is not) for believers always takes place in this life with its trials and temptations - as can be shown (even the Lord was "perfected"/completely victoriously tested in all points here) - with the only alternative being that of being lost:
But when we are judged, we are chastened of the Lord, that we should not be condemned with the world. (1 Corinthians 11:32)
As many as I love, I rebuke and chasten: be zealous therefore, and repent.
Indeed, and only those who overcome/persevere in faith in this life will realize eternal life:
He that hath an ear, let him hear what the Spirit saith unto the churches; He that overcometh shall not be hurt of the second death. (Revelation 2:11)
He that overcometh, the same shall be clothed in white raiment; and I will not blot out his name out of the book of life, but I will confess his name before my Father, and before his angels. (Revelation 3:5)
What you are doing is trying to use the principle of punishment to read purgatory into a text in which nothing is said of a place of reformation or purifying, but only that of being condemned with the world. Again, give it up as it simply is not there and never will be no matter how much you may want to read it into the text.
I notice the tender "Little flock." I also see three levels of judgment, with the first seeming fatal and assigned to the unbelievers. The next is beaten with many stripes for playing instead of watching and working. The last is beaten with few stripes because his lack of works was due to ignorance. Neither of the latter two classes of servant behavior result in assignment to portion of the unbelievers. The Messiah sums it up with saying more is expected from those servants to whom much is given.