Is double vaginal penetration that much different from a really girthy dick?

Been married five years to a woman I love having sex with, and only recently has she admitted that since our daughter was born, sex has felt “loose” for her, and then told me she’d just recently started doing kegels to try to bring the sex back to the greatness she used to experience before our child.

I looked into it myself and found a lot of recommendations for pelvic physical therapy, and she’s got an appointment made already. In the meanwhile, we still have pretty kinky sex that I enjoy immensely, and I give her oral sex until climax every time we do the deed. She’s always been a fan of double penetration, and has a dildo that’s roughly similar in size to mine that we use in her vagina whenever I go in her butt. The other night though, I thought I was going into her butt and unknowingly penetrated her vagina alongside the dildo, and she protested at first, but didn’t use her safeword, so I basically told her to quiet down, and banged the hell out of her with a dildo under my dick for a good ten minutes.

I didn’t even realize that’s what had happened either. She had to basically ask for more later, and told me what I had done. I was confused as hell, because i didn’t even think DVP sex was a thing, but she assured me it was, and had me pull up porn showing two penises inside a vagina, even triple penetration with a guy in a girls ass and and two guys in her pussy. She assured me that she didn’t want two guys, just me and a dildo would be great,

Is there really that much difference between doing double vaginal penetration vs a fat dick? Cause if i just need to buy a huge dildo to help get her off from time to time, I got no problem with that either. I just worry she doesn’t want to hurt my feelings and make me feel like it’s a me problem by saying that.