David Barnett
Only last month somebody told me about a seller at a small local show who said he was 'homaging' another's work, without attribution, of course, when asked about its striking resemblance to the originator. When she informed him who she was (the original artist), he didn't believe her. Turns out he'd copied from another copier, anyway.

As for unconsciously imitating, it can happen to anyone, but artistic integrity means doing as you do, Thomas. Of course, there are degrees of similarity and it's often difficult to not rationalize what differences exist between the new and original, but if the underlying idea's the same and one's re-expression is not significantly novel or distinct, then yes, it should be set aside.