According to the OED, the word 'nearly' has six distinct meanings as an adverb, and one more as an adjective. There are also a number of special compound forms listed, such as "nearly new" and "nearly man". Which leaves undefined the compound "nearly nearly", as in "we're nearly nearly there." If one treats the first nearly as an adjective modifying the second nearly, which in turn is an adverb modifing 'there' in this case, then it is clear that being "nearly nearly X" is equivalent to "nearly (nearly X)", i.e. "almost as near as nearly X, but not quite as near." But of course if the first nearly modfies the same root as the second nearly, then it is an emphasiser to be interpreted as "(nearly nearly) there", i.e. "even more near than nearly X is". So being nearly nearly there is either more nearly than being nearly there, or less nearly than being nearly there. With me?
After Zeno of Elea had proved that "that the flying arrow is at rest", the Greek army disbanded their archery division and replaced them with a platoon of mirror-wielders. They would focus beams of reflected sunlight onto the shields of opposing armies, causing small fires to break out. Sadly, the entire platoon was wiped out during an ill-conceived pre-dawn raid.