Its lovely being pregnant at the same time as a sibling.
It was so nice having my sister pregnant at the same time as me, as a young mum it was VERY scary and havin my sister around to comfort me and tell me the silly niggles that you have are complelty normal was lovely.
Having the babies at a similar age is also a lovely experience, when they are together playing its nice for them to have a little friend whos family..