Hi,
It won't be safer to store several currencies. Generally speaking, people invest in different cryptos to mitigate the risk and to avoid complete loss in case of erratic moves for one currency.
But your wallet won't be more secured if you have several cryptos.
Please, remember that bitcoin is not merely about trading. Most cryptos have a purpose and represent something. There were created for a reason, so learn about it before investing!
Hi m0gliE, I think that the OP ment buying another hardware wallet, not buying another cryptocurrency, for security reasons.
Anyway one scenario that I can see a benefit of having two hardware wallets is using one to hold your founds and using the other for everyday expenses or to sell some of your bitcoins to localbitcoin dealers - it may not be very safe to go around with all your crypto holdings on you.