I love these topics! hahahha
Anyways, correct.... The number of results showing is NOT an indicator of competition. It's mearly a number of pages google found in it's index that happen to have the same words or groups of words that you typed in.
The problem you're speaking of tho is not something to be concerned about. The two separate terms should be looked at side by side... not together.
The term you're getting #1 for probably has so little real competition (if any), that by G's algorythm, you just happen to land in the right spot.
The term that you're targeting tho, might have 10 - 20 people competing (REAL people, actually COMPETING). Which would explain where you're at.
People type in all kinds of crazy stuff when they're searching for things. Heck, one my sites (very low key compared to many people here) gets visits for up to 250+ terms a week... all in the top ten of course. Do I actually target them? Heck no... google just found the same text in my content, and my content happens to be backed up with many links, PR, ect.
Either way... this should be the last of your worries, and you should be glad that you're number 1 for another term... without even trying. ;)