Royal Signals NI beret badges

[sarby54]

Hi All.

I am gradually putting together a small collection of Corps badges and brooches.
I have a query that I am hoping someone will be able to help with please.

In Major A.G. Harfield's book, 'Headdress, Badges and Embellishments of the Royal Corps of Signals,
the woven OR beret badge is shown on page 14, figure 17. (If you have a copy).
It shows an oval badge on a black background.
I have one of these badges.
I also have a round badge on a blue background.

Were there two patterns of badge produced for N.I.?
If the oval one is the 'correct' one, what is the round one for?

Thanks, Nick