I've seen this behaviour before, though it normally occured when the SSIS package files where copied and the GUID's didnt get reset.

I think it had something to do with the way BIDS formed its stack, it was especially prevelant if one of the copied packages had been executed previously, it would then execute both packages, and if one completed first it would rase a completed back to the parent level even though the 'real' one was still running.

I hope that made sense.