I'm not sure it is. There is a 'scratch' but the (few) I have handled have always had a much more definite (deep) stamping and the 'scratch' seems to run into the 0 whilst the ones I have seen there is a normal spacing between the - and the 0
For the sake of about $1 a piece why not get one of each a - 015 and a +045 then you are covered and only paying one freight charge if you have bought the wrong size.