Interesting experiment, however I would be careful about reading too much into whatever results you end up with.

For one thing, the difference in population alone, 34,500 vs 31,900 (8.2%) should cause a difference in yield, as point out by another poster.

Another factor that may affect yield comparison is the relative spacing of the adjacent paired rows. In the second photo you show the "delta" spacing (adjacent seeds staggered 50% not next to each other) which is ideal. I don't know how you got that other than by accident with two passes.

Depending on the weather from here on out, you will probably show a yield increase on the twin rows. I urge you to be careful about making conclusions. jmho.

Jim at Dawn