How can you tell it is from a different maker?

Because the Dolls Head on a Webley Screw grip has
a Spade shaped head, this is more square, rectangular.

See the thread Marrakai pointed out plus pictures - I think some pictures exist of 2 of my 500 Nitro's on the fourm which shows both a
Webley Screw Grip and a Webley PHV1 next to each other.

In regards to the Stalking Safety (what I call it),
From what I have seen / owned they are NOT Automatic
and don't generally get knocked into position.

I wouldn't remove it.