My bf and I definitely got rid of some stuff when we moved in together (ditched my shitty Target desk in favor of his marginally less shitty Ikea desk, etc.), but held on to some doubles to the extent we had room. Like, we had two brooms for a while but then one just … went missing? Two vacuums, but then one got full of my constantly shedding hair and the motor blew. So it was nice to have back-ups.
We got rid of some duplicate books we had both already read (mostly in subsequent moves when we purged as we packed), but we still have two copies of Season One of Friday Night Lights on DVD. We’ll both need that if we ever break up.