That likely won't hurt it, the movement would simply be a little faster thru the narrower one. On my 3x5 flue pan, there is just one divider and it is open top to bottom at the end about 2" wide. When it gets into my syrup pan, 3x3, I have 4 channels. There are 2 draw offs, one on #1 and one one #4 counting front to back, they flow across the pan. The cut outs at the draw boxes are half circles, 3" wide and 1.5" high. The cut outs at the opposite end of #1 and #4 are 1/4 circles, 2.5" tall and 2.5" wide as is the cut out on the draw off end in the divider between #2 and #3. I reverse flow by closing one 1.5" valve at one end and open a1.5" valve on the other end. Mine has a 1.5" SS tube running from the flue pan, out past the draw boxes, then just out past the draw boxes to the other draw box. Same side draw. I've since seen even better set ups where you can reverse flow but you always draw off from the hottest channel.
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.