That's very interesting. If it is the same female ... she's one busy mama!!
I found this to be very interesting reading (copied and pasted from the allaboutbirds.com site):
Male House Wrens start building several nests at once in hopes of persuading a female to mate with him. Pairs typically break up by the end of each nesting season and choose new partners the next year. House Wrens are aggressive. Single males sometimes compete for females even after a pair has begun nesting. In about half of these contests the outsider succeeds in displacing his rival, at which point he usually discards any existing eggs or nestlings and begins a new family with the female.
