Drew and Meg generally met major motor skills goals at about the same time. It went back and forth who went first
Drew was the first to move in the crib. We had them both in the same crib after they were born. One morning we came in and Drew had done a 180. It was time for separate cribs.
Meg figured out how to roll over first. Can't remember which direction at the moment. Probably front to back. This was followed by many weeks of putting out the blanket for tummy time and then cheering when Meg or Drew rolled over.
Drew learned to sit up first. Sitting up was a nice phase. They could reach a few toys and not bother each other.
Crawling of course came in little bits. Meg and Drew both went backwards first. Drew did commando crawl quite slowly for awhile. Meg figured out actual crawling first. For awhile it looked like Drew was going to stick with backwards crawling and commando crawl, then Meg started crawling past him, stealing the toy he was playing with, and crawling off with it.
After a few crawl by toy stealing Drew figured out how to crawl forward quickly. Then they could take turns stealing toys from each other.