Fight club - temp girls

First off I got some major tooth ache last night, sleep was something I didn't get so I wasn't in the best of moods and I got into work later than I would have liked this morning, I work flexible hours so that's not a problem, but it was nearly 10am by the time I got in.

This is about two temp girls I have working for me, for the purpose of this article I'll refer to them as Joanne & Amy.
So Joanne's been working for me for about a year, she's a quiet girl who keeps to her self mostly but has made friends with most of the other people she works with, in December she had to go into hospital for an operation, nothing too serious but she would be off for about a month, she asked if one of her friends who was looking for xmas work could do the job while she was off, I didn't see a problem with this so said ok, her friend Amy came in about a week before Joanne was off and they worked happily together and got lot done, Amy is less reserved and made friends quickly, she also got more done in the day than Joanne did, Amy asked if she could stay on after Joanne came back to work, she was such a good worker and I needed a temp for maternity cover so gladly agreed.

Well today Joanne came back to work, my god! you would have thought these girls were each others worst nightmares, they were cursing and blinding at one another, Joanne was accusing Amy of stealing her friends and Amy was getting pissed off when people were being nice to Joanne, Amy then said she was going to quit, I had to split them up to get some order back, lets hope a new day brings with it some sense.