Why is the renderer exporting extra subset of frames

I’ve been trying to export a sequence with several nested sub-sequences. Every time I do this, I get two series of images instead of the intended one.

series #1: filename.0001.png
series #2 filename.-0001.png

In my example, series #1 will render about 7099 frames and #2 about 509 frames and there are 7600 frames total.

This is an image of the two streams in Resolve for a visual ref of what I am getting:

This is only happening with this nested sequence. It does not happen if I try to render a solo sequence. In that case, I would just get one series of 7609 frames.

Thoughts?