eilodon's bite evolution

[Kefler]

so if i only have 1 primary attack and it is a bite i get 1.5 str to dmg to it.

now if i take the bite evolution it adds 1.5 dmg to str . so do i get 2 times str , or it would have no effect ?

[Calth]

It has no effect until your eidolon gains a second natural attack.