Special Delivery Help

How could you find out if a Special Delivery E6 was a re-issue of 1909 with new plate(s) # 5420, 5423-5245. I was reading that after a few months of printing that the Bureau added a 09 to the plates. I guess any stamp could be plated but how is that accomplished or where would one search for more information on this subject? Didn't see it stating any color changed or perf change.Any suggestions would be appreciated.

Thanks Newby

There is no difference other than the plate number.

Hey thanks KGB. So, you would need a plate number?

Yes, I`m afraid so. (Like the one in the image above.)

EDIT: You could assume (and perhaps incorrectly) that an E6 1909 printing would be found on 1909 and later covers. There would be no guarantee of your being correct, though.

I realize that it's probably just a typo with digits transposed, but just to make sure the typo doesn't get propagated -- the plate numbers which ALSO exist with "-09" appended are:

5240
5243
5244
5245

Thanks KGB. Don't like to assume because you know what that means.
Khj yes a typo and thanks
for pointing that out.