Yes and no.

It was a coincidence inasmuch as (as far as we know) William of Normandy and Harald Haardraada weren't actively conspiring. William had spies on the English coast and they reported when Harold moved north to counter the Norwegian invasion and the men stationed along the south coast disappeared.

What wasn't a coincidence was that two different factions decided to invade England at around the same time. King Edward the Confessor died early in 1066 leaving a contested succession; the lords of England elected the Earl of Wessex, Harold Godwinson. William of Normandy and Harald of Norway both believed the crown had been promised to them - or at least that they could plausibly claim this and that they had the military cojones to back it up.

My main source for this is Frank Stenton's Anglo-Saxon England but to be honest it's a bit old these days and kind of a slog in places. I'm sure there are better histories of the 1066 campaigns specifically but it's not my speciality. Oddly, really, given I live in York. You'd think I'd know more about it all.