love the movie...
the professor,I assume has used the machine once and duplicated himself,found a way with his 'twin' to live together by disguising one of them,but switch roles every now and then
jackman character however,killed the first duplicate of himself,then found a way to make use of that machine in the magic,by drowning himself so that the duplicate from the machine will be the only one that alive,hence the 50 days only show,because I dont think anyone will go as far as killing himself for nore than 50 times.
need to watch the movie few times to get the idea.