Build for ARMV6 or ARMV7 but not for both?

if I select Universal ARMV6 + ARMV7 in my Unity player settings, I cannot access ARMV6 output in xCode, but if I say strictly ARMV6 only in Unity I CAN output to ARMV6 in xcode…

Why is this? Why can I not access ARMV6 output settings in xCode if I choose the Universal ARMV6+ARMV7 option inside Unity?

Thanks

Does this help?

http://forum.unity3d.com/threads/72350-arm6-and-arm7-questions

They seem to have both chosen.