D has two felony convictions acquired on the same day. He later commits an agg robbery, which is possibly a robbery of a street drug customer. We add a count of felon in possession of a firearm. May I use the other felony conviction to rep count the firearm charge, having used the other to make him a felon on that charge?

As far as I know as long as you don't use the same conviction to both get jurisdiction for the felon in possession of firearm and to enhance the offense, you are fine. The fact that they were disposed of on the same day does not cause a problem, as long as they are definitely two different convictions.

I am not finding any cases with a westlaw search. If anyone has one I would love to see it. I agree that intuition says it should be OK. They are definitely two seperate convictions....one a revocation and the other the felony that formed one of the grounds for the revocation.

Sounds like a righteous enhancement. Of course, the defendant will say that the conviction is not a "prior" conviction because one of the elements of the offense (the other prior conviction) did not occur after the enhancement. But, the CCA has rejected that thinking by saying the prior conviction is not an element, merely a status that elevates the crime to a felony.

Try starting with State v. Mason 980 S.W.2d 635 which says the date of the prior used in the primary count is not an element. The element is the fact that his is a felon.
This analysis is repeated in Cannady v. State 11 S.W.3d 205 (cap murder).
Also look at an old theft case called Menchaca 780 S.W.2d 917 that says the enhancement dates do not have to take into consideration the dates of the offenses used for jurisdiction.

Finally, a good discussion of this topic can be found in an unpublished Escape case called Ford v. State 09-02-050-CR Beaumont March 24, 2004. This guy has three convictions from the same time and the court said use one for the escape element and the other two for enhancement to a third degree.
If this post does not make sense, please feel free to call me at 979 864-1666.

I'll be reading those cases over the weekend, Phil. I may take you up on your offer to call next week.