While it may be a better idea to sand between coats, I doubt that you have done anything wrong by not sanding. Since the first coat was not completely cured when the second coat was applied, you now have a thicker layer of finish that needs to cure. I would just let it set for a day or two before I would take any other action. Keep checking it and see if it is starting to harden.

Also, two coats is enough to take your boats out and paddle them. I know of some who wait a long time (up to a year) before putting any varnish on them. If it makes you feel better, paddle them for a while and them add a couple more coats. Personally, I have 7 coats on mine, but it took me that long to get tired of the finish work. There were still defects, but I got to the point where living with the flaws was less painful than the thought of yet another coat of finish. Your threshold may be much lower.

Once you have them on the water, the memory of all the effort of creating them will fade away. You will also have a better idea of how perfect your finish needs to be.

Hope this helps.

Steve