Neuro LoR - Lab, Research, or Prof?

[Sakashi]

I'm having a bit of a dilemma in who to ask for a letter of recommendation. I'm currently 1+ years of research in a lab with a PI, Research Associate, and Post-Doc. I did 2 years of research in undergrad with a professor (who I had not taken any classes from). I had been planning on asking for LoRs from 1) my undergrad research prof, 2) the PI of my current lab, and 3) the Research Associate of my current lab. I work a bit more closely with the Research Associate than I do the PI, just due to the fact that the PI is busy doing PI things like writing grants. 

However, it occurs to me it might seem sketchy to have two LoR from the same lab. Is this the case? I have the sinking feeling it is, especially in a lab as small as this one. My other options are getting a LoR from a professor I had in UG who really liked me and I did well in their course, but that was a year and a half ago (I'm post-grad now). I'm applying for Neuro programs, with a focus on behavioral neuro research. My current lab is not behavioral really, the undergrad researcher was in the psych program but we did biopsych/behavioral neuro research, and the undergrad professor was in the psych program and one of the classes I took from her had to do with animal behavior.

Edited September 19, 2017 by Sakashi