Dogs weeing in their own bed- at my wits end!!!

[Sweetspidey]

We have two dogs, both are fully house trained. One of them is a rescue (who I believe started this disgusting habit). They share a bed and over the last few months they have started weeing in it. I rarely catch them doing it, but the smell is obvious, and I have on a few separate occasions caught each of them having a wee in there so I know it's both of them.
How can I stop this? I am sick of the smell, constant bed washing and dog bathing. Have tried belly bands but these just end up getting wee'd in aswell as he doesn't realise he's wearing it.
Help please 😭

Throw the bed away. Clean the bed area with the special cleaner. Go back to basics with toilet training.
‘Are they both males ? Might be territory marking if so.

@DustyLee123 thanks for the reply.

Do you mean chuck the bed completely? Or replace it with a new one? I replaced the bed with a new one about two weeks ago thinking this might help but it hasn't.
One male and one female (rescue), I believe it was started by the female and the male then copied. Other than that they are fully housetrained so I did think it was some type of marking behaviour

Do they have to share a bed ?

@DustyLee123 no they don't have to but they originally had a bed each and always ended up sharing, so we just got rid of one as it was pointless. Would be happy to get them one each if i thought that was a solution.

Are they both neutered?

Sounds like scent marking. She starts it and he comes along to pee over her scent to mask it.

You should also have her checked in case she has a UTI.

What age and sex are they? Older spayed females can have continence issues.

@FartSock5000 thanks. They are both neutered. She's going to the vet next week so will ask them to check her out for that

@Eyesopenwideawake

Male 3 years old
Female 4 years old

I don't think it's incontinence, I've caught her doing it a couple of times straight after coming back from a walk

I don't think they are entirely happy sharing a bed, hence the marking.
I would change things around: two new beds that can be cleaned with enzyme cleaner. (Vet bed and plastic bed is good for this.)
Then change the location of the dog beds if possible. Allocate each dog a bed by giving a chew, treat. Teach them the "go to bed command" and make sure each goes to their own bed.
I would do this every time you leave them, treat in their own bed.
Wash the bedding regardless every other day and obviously when it's been marked.

In time, this should sort it.

And even if the 2nd bed is 99.9% of the time empty, please ensure each dog has their own space!
There may come a time when it's necessary for them to be separatedadue to ilness ect.