I don't know if this bug is already known, but buffs can be used twice, once on i friends island, and once on your own... This gives a major advantage to players exploiting the bug, so in the name of fair play it should be fixed ASAP... I won't reveal details of how to achieve the double buff here as it is a public forum, but if the developers read this and need further info to reproduce the error, feel free to contact me...