"Instead of being deployed separately, bolt shooterS may be attached to a unit of legionaries.

There is "plural bolt shooterS" at the beginning and singulars unit of legionaries later.

So 1 bolt shooter converts one base of legionaries but 2 should convert 2 bases.

Hello

Special rules state that i Can add nolt shooters to Legionares base in Early Imperial Roman list.
Can I add two bolt shotters to single TUG of legionares?