I have a avid matchmaker that I got with my new front brake so I needed one for my left hand set.
I bought matchmaker “left” but this turns out to be the same as the one i already have.
So when calling it “left” they are referring to the fact the shifter is shifted to the left of the clamp and is for the right grip or was the wrong thing in the box?

I don’t know mate – not sure on their terminology. Is it a US / UK issue with the brakes being on opposite sides?
You can run the same matchmaker either side in a pinch – the positioning of the levers won’t be spot on, but it’s perfectly rideable. I guess you would want to send the wrong matchmaker back without using it, but if you had a ride planned that you really wanted to do you should just slap it on.

Having had another look at some google images it looks like the one I’ve have for a while should been on the left even though it was from a front brakes. Is it only the UK that front brakes off the right lever?
So what I’ve bought is correct but i prefer the feel of the wrong one, go figure.

US front brake is on the left, so reversed from the UK. Think European bikes are the same as the UK (front brake on the right), but not completely sure.

Avid brakes are reversible so US/EU/UK is irrelevant.

Post pics of the matchmakers you have and we can tell what’s wrong. I have a set of Juicy and a set of Elixir matchmakers.

I stopped reading when I read the word ‘Avid’. My recommendation; buy some Shimanos

Which has nothing to do with the issue at hand.

It hasn’t, but it sure as hell will solve it and save you countless hours of frustration and ruined rides with seized pistons and rubbing brakes in the long run

I have none of that experience.

Though in the long past I did have frustration with Juicy 3. They were a bit rubbish (though never ruined a ride), but stick with any Elixir derivative and you’re fine.

And how does just switching to Shimano solve the issue? He’d be back to separate levers on the bars or change all to Shimano and get into the world of i-spec with just the same if not worse issues.

Matchmaker is pretty simple really and quite neat. Even integrates a reverb (quite nicely with a 1×10 set up joining the lever to the left brake lever).