I planted 3 cucumber seeds in each of 6 hills and only 6 of the 18 cucumbers came up. Of the 6, only 4 seem strong enough to survive and 2 of those are in the same hill (as shown below in the first two pictures).
I've read that the best thing to do is to cut off the weaker seedling at ground level to let the stronger seedling take over. Is transplanting out of the question? I would assume so since there is so little space between them but would hate to be down to just 3 out of 6 hills with plants.
I gave transplanting a shot and moved the smaller plant to a hill a foot away (as shown in the last picture). It's only been a few hours but so far it survived. I'll keep my fingers crossed.