Hi, I've done a masters in 2010 from the UK (social science) and the result was really not worth mentioning, just a pass (53%, dissertation 63%). I've got another funded opportunity for a two-year Erasmus Mundus MA which I'm currently pursuing, and after completion, I have plans to apply for a PhD in UK universities.

Would it be wise to avoid mentioning my first MA when I apply for the PhD? the first MA grades are so bad, with one module I had to retake to pass, also includes a condone (this was an unfortunate experience, I won't go in detail). I have a 1:1 bachelors/honours from outside the UK and IELTS 8.0 (2009) - just to indicate that my first masters was a really unfortunate experience and doesn't reflect my academic career. I have 7-8 years of relevant professional experience and a recent TOEFL score (2019) of 104/120.

Grateful if someone please enlighten.

If you focus on doing really well in your new Masters programme your old grades won't matter.
I won't harm you to mention it as long as you can show you've fixed whatever problems you had at that time.
I know people who did a Masters to fix a 3rd class honours degree and then went on to do a PhD.