So, rely on one gun instead of two? While very unlikely, there potential is always there for a crippling issue to happen to the first gun, be it a squib, a kaboom, a broken firing pin, a split case or a case head separation. Those are things that cannot be fixed with a tap, rack, bang.
The backup gun is there for exactly those reasons and the benefits of it are pretty valuable such as an extra gun to arm another person, so it's possible that you could not only save your life, but someone else could save theirs.
It's said so much, but a reload during a DGU is practically never needed. That would lead one to question what the value of a BUG is, but I do recall seeing somewhere a guy in South Africa used an NAA to fight off three muggers and in the process his NAA blew up. Like, good thing the other guys robbing him started running as soon as the first perp went down with a shot to his chest otherwise Boer would have been dead meat.
That said OP, I would gravitate more toward a P32 than an NAA Wasp. I too thought NAA was the only option for a super tiny, small caliber, lighter recoil gun for deep concealment, but I recently got an H&R Young America .32 and man, for a design that's over 100 years old it is so superior to an NAA mini revolver and costs half as much. Very decent DA trigger too and it only weighs 8oz.