You are referring to the signal at MP422 for westbounds on track 1. This is the depot departing signal, its function is/was so that westbound passenger trains aren't delayed in block on departure. It is a distant signal to the next control point west (CP-423) hence the two signal heads. With a clear indication trains can accelerate immediately to track speed. I'm not sure when it was installed but clearly is of NYC vintage and has US&S Type G heads.I have a sneaking suspicion the oddball westbound only automatic west of the Amtrak platform is now gone.
I always liked this signal with its offset heads, even if only visible at a distance. I think the Amtrak crews and passengers appreciated it too!