The "personal a" is not necessary.
Tengo dos amigos.
Translation: I have two friends.
Explanation: The "personal a" is a preposition that we use when the direct object of a sentence is a person.
But there are exceptions to the "personal a" usage rule:
When using the verbs "tener" or "haber" we don't use the "personal a".
In this case we are using the verb "tener" (tengo), so "the personal a" is not necessary.
Spymore