Can I use two Ace headphones at the same time for TV audio?

Yes. Originally, using two Ace headphones at the same time for TV audio wasn’t possible, but a software update added this feature.

So just to be clear, it was a software update and not hardware...meaning that any two Sonos Ace headphones will work?  I was planning on buying two headphones for this purpose and want to make sure that it doesn’t only works with a certain model Ace. Thanks!

It was not a hardware thing.  All Ace headphones support two units connecting to a Sonos soundbar at the same time.  

And there is only one model Ace.

Yes. This is the case if the TV has two headphone outputs or you use a headphone splitter. Or also a Bluetooth transmitter that supports two connections, then both users can listen at the same time.

Yeah, that would apply if Ace was just a Bluetooth/analog headphone.

But it’s not . . . 

​@sandra_p This thread is about the Ace’s TV Audio Swap feature: https://support.sonos.com/en-us/article/listen-to-your-tv-with-sonos-ace-tv-audio-swap

”A maximum of two Sonos Ace headphones can be used together in a TV Audio Swap session.”