Maker and date discrepancy Dublin 1739?

British Silver Reading Silver Hallmarks
1

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?
Thanks

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2

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

3

Thanks for the input on most likely solving that mystery!