James,
Not saying this is definitive but I have AP2's & 3's on AMT red shafts.... The numbering convention on mine is the same font and computer numeric (ie crossed) zeros as the right hand image in your second picture.
My irons were ordered from Titleist after fitting at a Titleist Advanced Fitting Centre so I'm pretty sure they are pukka.
My woods and U500 came via the same route and the font/number set is different to the numbering convention on the irons.
In normal circumstances, Luke, one of our Team Titleist co-ordinators, would be able to check the numbers for you but I'm not sure that applies at the moment.
Sorry I couldn't be more positive.
JT

I have T200 irons and the font on them is the same as the left hand pic.

Might be that one is OTR and the other was a custom made order with adjusted lie?

IA
Mine were custom order as they were a combo of AP2 & AP3 - They were fitted and came adjusted to a 3* flat lie...
JT

I have a set of T100S that were order direct from Titleist and they have the computer etched without the crossed 0 on all of them, if they are a custom set all irons will have a serial number, or if std (from AG) just the 6 iron will have the serial number.

my custom irons direct from titleist are the same style as the right hand picture and can feel the digits. as above as they are custom, each iron has the same serial number so can be traced back to what loft and lie etc

Have you tried contacting Titleist UK, I had similar concerns regarding AP2 I bought on eBay, I sent them to Titleist through my Golf Club professional, Titleist returned them to me within a week with a letter confirming they were genuine.
Just another example of the excellent customer service Titleist provide

I have custom fit T-series irons from 2 suppliers:
First set, direct from Titleist UK have serial numbers as per the left hand photo.
Second set, from Scottsdale Golf, are also as per the left hand photo.