I hear your pain! My two are 16months apart and I write this after having just tried to sneak into the bathroom to go to the loo in peace. NO CHANCE! DD came in and wanted to empty the nappy bin of it's contents to get at a broken toy in there, DS was trying to put his hands through my legs to get at the toilet cleaner thingy. Then DD wanted to go to the toilet too (she's toilet training) when all I wanted was to get them out of the bathroom. so I put her on the loo and took DS into the bedromm only to return to DD having emptied a half full toilet paper roll everywhere and trying to put on my lipstick.
I rarely go out anywhere without DH. DD is a runner and is so not worried about if I'm with her or not and she will not sit strapped into a pram, hold hands and nor will she wear a harness. A trolley is a good option for us too. DS is ok in the pram though will start to scream after an hour or so. But I just choose to minimise my stress and don't go out with them both. If I have to go anywhere one or both stay with DH or he comes with me. Sometimes I will get mum to look after one or the other if I really need to.