Can you place two access points side-by-side?

Are you experiencing any issues with the wifi with that setup?

As a general rule, I would normally say to keep two transmitters in the same band, even if they're using different channels, as far apart as is practical. At a minimum, at least one antenna-length apart. If they do not have external antennas, then just assume it's the length of the chassis and use that for spacing.

But if it's working fine as-is and you can't or don't want to adjust the spacing, then just roll with it.

You mean they provide access to two physically separated networks?

Generally the way you would do this kind of thing is with VLANS.

If you can't do that kind of logical separation of networks and need to keep it physically separate that way, it's probably fine to have 2 access points (1 for each network) but based on simple physics, I would either not want them close, or I would want them essentially as close as possible. it depends on how reliable the channel configuration is and the quality of the hardware, the wifi version in use (newer ones are better at not stepping on each other and are more efficient).

But yeah, I would simply position them as far apart as you can given the design of the room and cabling and stuff, at least 6 feet or more just for all the other EM interference they probably generate, even if they are being respectful about their actual wifi transmissions.

If you can't do 6ft and it works ok, it's probably fine. The main issue I have see with wifi being 'too close' is client to AP not working at all because the fresnel zone is extremely small right next to the AP/client so the client can't get a reliable connection if it is within a foot or so.

If they're well made, they shouldn't interfere with each other with that setup, but they're likely cheap consumer crap, and there's no way to know how good they actually are without some kind of meter and lengthy testing.

As both @Kyuu and @Paladin are suggesting, splitting them up even a little bit will reduce potential interference a bunch. The inverse square law is your friend. Even a foot or two will be much better than immediate adjacency. I would think six feet would reduce accidental interference to about zero, unless one of them is pathologically screwed up.

In my experience, having access points (APs) too close with non-overlapping channels can still cause interference, especially with 2.4GHz. I'd say try giving them some more space, maybe a few feet or so.

Ok, so after the fact:

You’re probably fine. But you could try a test where you run at max bandwidth over one, and then see if that drops if you start doing the same over the other.

I can tell you that interference is real, with my bluetooth mouse becoming pretty much useless with much data going to the access point 30 cm away from it at 2.4 GHz. (Many years ago.) But BT frequency hopping and 2.4 GHz Wi-Fi clash more than two reasonably separate 2.4 GHz Wi-Fi channels. Note the channels 1, 6, 11 thing is not 100% correct, there is still some overlap. If you’re in Europe, 1, 7, 13 is better. Or if you only need two channels, 1 and 11 or 3 and 10 or 1 and 8 or something.

On 5 GHz the channels don’t really overlap.

If interference is a serious problem, it might be better to run the different APs on the same channel, as this way the carrier sense logic will work as needed and the different networks will share the one channel running at maximum speed, while if they’re different channels but with some overlap and thus interference, they may not see enough activity to wait transmitting, but it might be enough for the reception to be unsuccessful and it has to be retried at a lower speed.