Mint Error or a New Variety?

CNG 108, Lot: 728. Estimate $500. Sold for $450. This amount does not include the buyer’s fee.

Maurice Tiberius. 582-602. AV Solidus (21mm, 4.24 g, 6h). Light weight issue of 23 siliquae. Constantinople mint, 1st officina. Struck 583/4-602. Helmeted, draped, and cuirassed bust facing, holding globus cruciger / Angel standing facing, holding long staff surmounted by staurogram and globus cruciger; A//CONOB. DOC (7a) var.; MIBE 11 var.; SB 481 var. (all with star on obv. and rev.). Superb EF. Unpublished variety, or mint error using dies of SB 478 on flan of SB 481.

There are three possibilities regarding the attribution of this coin. The types are that of SB 478, regular weight solidi, while the flan is that of the light weight solidi, SB 481. Other than the weight difference, the coins of SB 481 add a star to the obverse and reverse type. One possibility is that this coin is the result of a mint error, where dies for the regular weight series were mistakenly used on light weight flans. Another is that the mint had to strike light weight solidi before the dies were made with the star added to the types, so pre-existing dies from the regular weight series were used. A final possibility is that the light weight series began with the exact same types as the regular series, and the star was added shortly after to distinguish between the two denominations.