What would you do?

A couple of weeks back Moo got invited to a Birthday Party, Boo didn't get invited. Before the invite even made it home, Moo & Boo's teachers figured Boo hadn't been invited and approached the mum to ask her if she was aware she had invited one twin and not the other. She of course didn't, was mortified and let them know she  would bring an invite in for Boo the next day and to let me know she was invited.

When I arrived to pick the girls up from Kindy, Moo's teacher informed me on what was going on. I was touched that the teachers took the matter and Boo's feelings into their own hands and sorted it all out for me. It was really kind and very unexpected. I'm also very touched that the Mum went out of her way to make room for Boo and reacted in such a generous and thoughtful way. Woodi (hubby) and I have talked about this scenario before, we're aware that it would happen eventually and that we would just have to find the best way of dealing with it. Not everyone can be expected to invite both girls, especially if they are only friends with one! But we were relieved and thankful we didn't have to deal with it just yet!!

So.... being that this party was at Lollipops (one of those indoor playground/party places) and the other Mum had to pay extra for Boo to come, I made sure I was generous with the gifts and gave individual ones from both the girls. I thought they were separate invitations, the Mum was paying to have both the girls there, so it was only fair. The Mum picked up on this and informed me that I didn't have to get 2 lots of presents, but I told her I felt it was the right thing to do & I was very grateful she went out of her way to accommodate us.

NOW... here lies my Dilemma the girls have both been invited to another 2 parties this weekend (one Sat & one Sun). I don't know if they were both invited to each originally or if exceptions were once again made, both the parties are at the kids homes. My Mumma told me not to go buying all these kids 2 lots of presents... but I did. Truth is it's costing me a fortune, but I'm just not sure what the etiquette is??? Am I setting a bad precedent or am I doing the right thing? Do I just send my girls with joint gifts in future or one each?
If I keep buying 2 presents each time I may have to put a limit on the parties the girls attend.... then again I'm wondering by giving out a present each will the word get out and will it help with the problem of the girls both being invited to parties??

Ahh my head is in a spin, my pockets are empty and I wanna know... What would you do??