First off, holy cow those are some cute sweethearts! I just want to reach thru the screen and squish those cheeks! I miss my little guys chubby cheeks!
I think you're starting to enter the 2-1 nap transition and also need to get rid of the shush pat. They don't need it, and it's becoming AP by now, I think. I think even though they are still napping well, they just aren't as tired as they were. 3 hours is a pretty short A time for 13 months. I'd try moving that AM nap by 15 minutes for a few days until you reach about 10 am. See how they nap at that time and for how long. If your PM nap is still tough, then I'd limit AM nap to 1 hour and let them sleep as long as they want in the PM.
Try with changing AM nap first, and see what that does for PM nap. If they're still playing too much, then push PM nap a bit later too. Even though they are showing sleepy signs, sometimes it becomes a habit -- they've been on the same routine for awhile, and so their body shows sleepy signs at the normal time even though that's not exactly how they feel!
As for eliminating the shush pat, I think I would just do it for a little while, and then leave the room. If they play, they play. Only go back in if they cry. Now, with twins they're going to rev each other up! So, what you might want to do, in addition to moving nap later, is extend wind down for a while to get them in a more relaxed state before nap. I think the combo of having them MORE tired at nap time + a longer wind down might get you to the point of having them go to sleep independently without your patting!