It'll draw the same texel multiple times if it has to. One of the Saturn's programming manuals describes in limited detail how it will attempt to avoid leaving any gaps in polygons.
> Polygons contain diagonal lines that may result in pixel dropout (aliasing). When this occurs, holes are anti-aliased. For this reason, some pixels may be written twice, and therefore the results of half-transparaency processing as well as other color calculations cannot be guaranteed.
> Polygons contain diagonal lines that may result in pixel dropout (aliasing). When this occurs, holes are anti-aliased. For this reason, some pixels may be written twice, and therefore the results of half-transparaency processing as well as other color calculations cannot be guaranteed.
https://antime.kapsi.fi/sega/files/ST-013-R3-061694.pdf