protect yourself at all cost, on this case your coins. just having one wallet is very risky as you can lose all of them at once. there's no harm in having a back up storage
It's the same as putting a ton of your money into a single investment on the stock market, it is risky and if something happens with it then there is a high chance that you can lose all of your money in one fell swoop. The big advantage of Bitcoin is, however, the ability to copy your investment so there isn't just a single record of it.