I'm usually a 1 on the hip, one nearby kind of person. Sometimes in the winter or in situations I'm forced into that I feel are unusually unsafe I'll use my spare G22 as a BUG so I have 2 G22's with 15 rounds each and a spare mag.
1. If someone gets the drop on me somehow and I'm forced to disarm myself, I'll have another in reserve.
2. If I somehow damage my primary, I'll have a backup.
3. If I get in a tight situation and need to separate from my wife, I can give her my backup as a last ditch defensive act. (I'm working on her getting her own permit and carry piece but it's a long slow process with her).
In the winter I have been known to carry my 1911 in a shoulder rig under my coat in addition to my G22+mag on my hip. I've also done this (or something similar) to almost every wedding/funeral/family event I've been to for the last 2 years because the 1911 was my Father In Laws and I like to keep him close at family events
Well, there would be several valid reasons to carry a back-up gun. The most obvious is failure of your primary weapon. While I agree that reliability should be tested and tested again before choosing your weapon, failures do indeed happen with well tested equipment. We jumped with a reserve chute, would you go without one?
An unlikely but plausible scenario (amongst the already unlikely scenarii requiring you to employ your primary weapon) where a secondary weapon could come into play is walking into your house to find a family member already held hostage by more than one home invaders. It is likely that a primary weapon carried on the hip, concealed or unconcealed, will be taken from you. I suspect you won't even resist, if your loved one is actively being threatened at that time. It is marginally less likely that a deep concealed second gun would be suspected and taken.
Having two is better than having one, especially when there is no particular downside to carrying the BUG.
adding a second firearm adds a lot of risk.
Once you add a second firearm into the mix, the prosecutor will do everything in his power to paint you as "someone looking for a chance to kill someone" and there's a very good chance the jury will eat that up.
IMO, if you feel the need to have a backup gun then you are not confident enough in your skills, training, and primary weapon's reliability to begin with. I agree that you can never have too much training and there is ALWAYS room for improvement of skill, however if you take your safety seriously enough to carry a gun to begin with, then you should be reasonably confident enough in your skills to put your life on them just as much as the gun. If not, then no number of guns is going to make up a difference for lack of training/skill in a real life situation. Additionally, one shouldn't put their life on the line with a gun if they don't feel confident enough in its reliability to begin with. If they plan on its failure, then they are to some extent not confident in its reliability anyhow and should find a better weapon ASAP or train with it MUCH, MUCH more to build more confidence in that weapon.
When has this ever happened? Ever, even once? In the thousands of self-defense cases, when has this ever happened?
Massad Ayoob discusses a case, in which he was an expert witness for the defense, where this exact thing happened... simply because the guy had 2 extra magazines... IN HIS CAR:
"The cops took the stand. Yes, said the arresting officer, he had been called to the scene of a crime of threatening to shoot someone without reason... found two complainants willing to testify... found the defendant who admitted having a gun just like the one the complainants had described... and determined immediately that he was guilty and placed him under arrest. Much emphasis was placed on the large caliber of the weapon. The prosecutor elicited from the officer that the hollow-point bullets, 230-grain Federal Hydra-Shok, were designed to expand and tear 'larger wounds.' And, oh my God, there were two spare magazines! Enough bullets to kill two dozen people!" The Gun Digest Book of Concealed Carry, pg 40 (emphasis in original)
If you don't think the prosecutor will use everything in his power to make you look like a gun-crazy lunatic just looking for a chance to kill someone, once he's decided to press charges, you're living in an imaginary world. If you think that a jury of anti-gun liberals will side with you (or it is worth the risk they won't), fine, but I don't see it as a worthwhile trade-off.
First, this doesn't sound like a self defense situation, but rather an intimidation case where the gun owner is the perp.! So, how does this have anything to do with the discussion?
Second, the first responder " determined immediately that he was guilty" really? Was his name Dredd?