Sirop, I would report this bug by the link in game.
It sounds like Sirop is saying they tried to merge the Lady Vamp and wound up with the merged Lady Vamp, an unmerged Lady Vamp, and a bonus Cow Curator?
As in:
BEFORE: Lady Vamp 6, Lady Vamp 6
EXPECTED: Lady Vamp 7
AFTER: Lady Vamp 7, Lady Vamp 6, Cow Curator N