Why have one when you can have two for twice the price?
I once ended up with two Jeep Grand Wagoneers at the same time due to my propensity for this strange logic.
I recently did the same when purchasing a second M57 two weeks after purchasing the first, but that was due to the insane value I felt they represent (and still do).
If you're not wanting to spend the money for a second G23, then know they'll be around for a long long time. Just purchase plenty of spare 13-round magazine in case you do purchase that second G23.
If you really do simply want justification for another G23, why not just go for it? It's not like you'll be out a ton of cash or end up with a pistol you can't use.