Chain pharmacy where i got 1st moderna shot was not enforcing mask policy & allowed several unmasked ppl to loiter in vaccine area where i and unvaccinated others were. uncomfortable w/going back. is it necessary to get 2nd dose @ same location?

You're right to be concerned; I hope your pharmacy changes its policy. But for sure get the second dose, even if at the same place. People are largely immune within 2-3 weeks of the first dose, so by the 2nd dose you'llalready be pretty well protected and at low risk from all those unmasked people. (Over time, we may learn the 2nd dose is important mostly to make immunity last longer.)