Is it possible to have the same wallet both on my phone and on my laptop and use them both or will this lead to errors?
Like he said, there wont be any problem.
But I wont recommend it, it'll double the risk to get hacked;
if you need a copy of your wallet in your phone for
checking balance/transactions, import the master public key instead to create a "
watch-only wallet".
But if you really need both devices to be able to spend your coins, yes, you can do that.