Your left hand stamp isn't 494... it's either 456 if watermarked,
or 493 if not...
Given the fading on your right hand stamp it's really difficult to
tell (what) it is... could be 456, 493, 494... check it for watermark...
if you see one, then it's 456... if not, it's 493 or 494...
I've added a larger, clearer scan of your stamps...

Note : SCF optimizer not working properly... I'll try to add larger image later...