I think it depends on how hard it is to get there. Personally I think for me it would have been easier to go to the doctor once for both boys, then to get there twice, so if they had been due at the same time I would have had them done together. But if you can easily pop out with one at a time atm (if DH is on holidays or something), then maybe space them out a bit. Whatever you do will be fine, I'm sure.