For 1970-S there are a lot of coins that seem to have thicker letters. But some of them are
DDO. Short of finding some exact die marker you may wish to look very closely and with different light angles at the lower left corner of the L in LIBERTY and the tops of the W in WE. That's where the doubled dies tend to actually show a bit better. And if you are really looking, a whole pile of the
DDO's for that year are just minor bars above or below the 7 of the date or bits above or below the L of LIBERTY. Lots of minor
DDO's to be found on that year so with a roll of good coins the odds are actually pretty good that something in there will be a
DDO.