Is it allowed to have 2 wallet with same email addresses ?
In coinbase you can have 2 or more wallets in only one email address. But in Blockchain one email address, one bitcoin wallet.
General rule - if you were not prompted, during account creation, to use another email address then it is fine to have multiple wallets linked to one email account.
But I am not sure if that is good idea, so don't do this. It is always better (and more secure) to have multiple accounts, each with different email attached.