I think you are okay. Don't trust that spec sheet. If heat isn't an issue and the plants don't wilt, try it. This would be more important for Bloom or if oyu need additional coverage in a loaded tent or something.
If your plants are growing well, it may not help. Your diary is just seedlings right now? Defintieyl don't do it now. I think you have plenty of coverage with 1 light at moment.