The problem is with how it happened for you. You did not have multiple packs of the same girl being treated as one pack. You had multiple packs of 20+ different girls being treated as one pack. The result was (to the game) a single pack with hundreds or thousands of images. So for any image from this pack, you could randomly end up with an image from any of the different girls.Is this necessarily a bad thing, though? For example, if you have multiple packs of the same girl from different authors and want the game to consider them all as one girl, e.g.
girl/girlpack_leortha
girl/girlpack_otherauthor
Would there be a conflict or issue in how the game picks certain images? Would the game still select pics from both packs?
So, if you want them as separate packs, which is what people generally want, then you do not want that behavior.
But, if you want to combine different packs from different creators into one pack, then doing what you describe would absolutely work.
I can see two drawbacks, neither of which is game-breaking like the "multiple girls in one pack" was for you.
First, you will have a larger than normal rate of duplicate images, as you will almost certainly have the same image seen across the different packs.
Second, if one pack is badly tagged, that bad tagging will now have infected the combo pack. So instead of one set that is well tagged and one that is badly tagged, you have one combo set that is badly tagged. Bad tagging is one of my pet peeves in the game. Seeing girls getting nude when the game has not gotten them that far. A girl having sex while walking around town. Things like that. Bad tagging has, over time, been the most common reason that I will take an old pack and revise it. But if that stuff is not as much of a bother, then it's not as much of an issue.