Nope - i have a few small pots with 2 geraniums in each that are doing fine. But, i reckon they would do better with a separate pot each.

I usually stick about 5+ cuttings in in a pot until they develop roots, and then transplant them into separate pots.

So i doubt that 2 cuttings in the same pot will kill each other, but they will certainly compete a bit.

In order to save space I have sucessfully rooted several Pelargonium cuttings in the same pot eg. five cuttings in a 5" half pot. Care is required when separating the rooted cutting so as not to damage the roots.