Ours aren't as connected as yours but DP and I worked out we were at the same Violent Femmes concert standing about 2m away from each other about 10y before we met. We even vaugely remember seeing each other when described what we were wearing.

Also we both had very extensive cd collections when we moved in together and like a lot of the same music but when we merged our collections we found that we didn't double up that much as the CDs I had by an artist were the ones he was missing. I had the triple j hottest 100 volumes that he didn't etc. so when our collections were merged they formed a complete set.