Maker and date discrepancy Dublin 1739?

These marks are on flatware that seem to indicate Dublin 1739 (letter T) but the maker mark “JO” appears to belong to John Osborne who worked in 1780s-90s. Has someone tampered with the marks?

See here on 925-1000 for a duplicate query. Incidentally, I agree with the answer posted there.

Thanks for the input on most likely solving that mystery!