As a ‘secondary’ weapon I would always try and discourage people from feeling that they need to carry a secondary ‘just in case’
We are playing games, you would get more value in making sure that you are familiar with your main weapon and that it is reasonably reliable and maintained.
The ‘worst’ that can happen is that your main fails and you get shot out, then have to walk back to the safe zone to resolve the issue
The ‘best’ that can happen is that you whip out your secondary and stay in game - but then you still have a non functioning primary that you need to sort out, which means when everyone else is having snacks and telling war stories whilst reloading you are trying to fix a problem in a rush.
If you need an alternate due to game rules, such as your primary is a sniper and there are range restrictions, or you are playing at varying engagement distances then you may need an alternate.
Otherwise it’s something else that you have to carry that is loaded and chronoed ready, plus you may need to prepare more magazines etc, and unless it’s a springer then need it gassed up / charged etc.
But there is “do as I say not as I do”
It’s fun to play with pistols or other ‘restrictions’.
I won’t carry a pistol on a holster etc as added weight, but I will play with twin pistols and leave the holsters empty while I’m in field - unless I’m doing something different such as carrying a prop/objective