My girlfriend and I, have done a lot of double penetration with toys with the toys taken anally while we have sex. This is actually how I eased her into anal play/sex to start as let the enjoyment of sex kind of act as a relaxation technique in getting her to enjoy anal from the start. If you want to know more about this, I did post in an
anal beginner thread about this.
Double penetration with toys, as the guy is interesting as you can feel the toys while inside your partner. We have used a multitude of plugs of increasing size up to a plug 5” x 1.25” in size. Even the smallest ones, that have finger loops to make using them during sex easier can be felt while moving them in and out of my partner. We've also enjoyed using our
Flexi Felix toy during sex, which results in a tighter and a more textured experience while having sex with my partner as the individual beads change the pressure on me while inside. My partner has expressed really enjoying this dual penetration/sensation of having sex while we use the Flexi Felix.
I also have a cheap vibrator that we've used a couple times to penetrate my partner anally while we have sex, which is an interesting sensation both on it's own and when the vibrator is engaged. I've considered getting a better/rechargeable vibrator to do this more often since we haven't done this since the batteries went dead, plus I'm not really sure what it's made out of. Regardless, can be a lot of fun if your partner is open to it.
We've tried vaginal penetration during anal once without success, as the position we were in resulted in my girlfriend being too tight for the toy we were using. We only have anal sex about once a month on average... kind of depends on our mood and available time, since it requires a lot more forethought and foreplay. As such haven't tried this again after that first attempt. I definitely look forward to trying either smaller toys or potentially alternative toys in this way in the future.
But holds true for DP as it does for anal: take it slow, build up to it, and communicate with your partner(s) to insure you aren't moving too fast.