usable by others simultaneously

[Beast]

in a character I'm working on for fantasy hero I came up with a marching song spell which has life support usable with others the amount of targets the amount of targerts affected is off by 1 level
when set in the "add modifiers popup" when set for 8 affected the onscreen final shows 16 affected
so I had to set it for 4 affected to get affects 8

this is in 2.0.45
I have attached the character

[Simon]

The number is not off at all.

Usable Simultaneously (obviously) means that it is usable by 2 people at once.

When you purchase a multiple on that, you are multiplying the number of people it is usable by.....x8 means that it is usable by 16 people at once.