Putting in a dedicated power line. 2 receptacles ok?

I would do at least 2. You might want to move equipment around in the future.
joenies

I assume you mean a double duplex (2 port outlet)or two separate duplex outlets. I would stay with one outlet/duplex. What I did is 1 20 amp for audio and 1 20 amp for video with the grounds on opposite legs in the breaker box.

 with the grounds on opposite legs in the breaker box.

<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>

I'm not following you. There are opposite legs in your breaker box for ground?

L1
L2
Common bus bar
(bridge bar (remove or leave) between common and ground)
Ground bus bar

Where is the second ground bus in a 220-240 single phase main?

L1 and L2 maybe.. Separate? Not a good idea that is how you get a ground loop.. Use only one dedicated 20 amp or a second BUT on the same bus, not the other.. L1 only L2 only, don't mix and match..

Regards