No, adding two, unless it is a HUGE tank (well over 200 gallons minimum) is a bad plan. If your Linckia is not over 18 months old or so, you have no way to know if it is fine. Most take a good year to starve, and adding another similar star will simply speed this up.
The "red bali star" apart from having serious acclimation issues like Linckia, is probably a Fromia and its specific diet is still unclear. It has been reported to feed primarily on sponges of various sorts (usually encrusting sponges).
All I can really do is beg you to reconsider unless this is a very large, very mature reef tank and you have had your Linckia well over a year. Keep in mind that blue Linckia, if healthy and finding enough food, will reproduce on their own. This, IMO, is the best way to add another star. It is rare for a blue Linckia to do this in captivity probably because very few are healthy and in a suitable size tank.
