when you store infused cigars in the same storage as regular cigars you risk inadvertently infusing the regular cigars to some degree. The regular cigars (and the wood in the humidor) can absorb some of the scent/flavor of the infused cigars, most of which have a very strong scent too. If the cigars are actually touching, some of the sryupy stuff that is on the actual flavored cigar can transfer over as well. The degree of how much transfer depends on a lot of factors which you can probably guess (amount, size, time, etc.). Not worth the risk imo.
On a side note, I remember reading about people purposely infusing their own cigars by a similar method, I do not know if it is true and works or how well it works though. Basically, from what I read, they would put a shot of whiskey (or any other flavor/scent they were trying to use) in a sealed container with the cigar they were trying to infuse and eventually some of the flavor would be infused in the cigar.