My Mac keeps adding double spaces randomly when I type I'm  running  Mac Version 10.14.3 on a 15-inch 2018 model.

I'm not sure if I received a new update but over that last few days it keeps adding random double spaces as I type.

I tried turning off key repeat as suggested on some websites but that hasn't corrected the issue. Has anyone else experienced  this problem?

I've had this Mac for several months and I never had this issue until a few days ago. I'm not sure if it's software or hardware related.
I had a client with this exact same problem late last year, turns out it was a faulty keyboard and not software related. I would recommend you check your purchase date, see how the warranty looks in your territory and take it back to Apple for advice and repair/replacement.

It's a known problem with some (but not all) 2018 MacBook Pros:


https://www.reddit.com/r/apple/comments/9isi10/mbp2018_spacebar_double_space_is_this_a_common/
https://www.laptopmag.com/articles/macbook-pro-air-keyboard-problems