My DD will be 2.5 when bub #2 comes along and I'm not getting a double, I've bought a 'kid sit' buggy board second hand (skateboard style attachment but with seated option) and also have the carrier (DD is still under 10kg!) if needed.
I guess it all depends how often you use it and what your toddler is like. I may have taken my pram out once in the last 6 months aside from walking on weekends with hubby and walking down to my mum's house. For the long weekend walks I've bought a stroller for DH to push with DD if the distance is too far and no one wants to use the carrier.