Originally Posted by
Trialgame
Not Quite. There is absolutely zero value to upgrading the second one. Doing so would imply you intend to use both functionally, however since the cooldown is shared, you would only be alternating between the two. That means area A would be buffed for 12 hours and then unbuffed for a minimum of 9 hours while the counter cools down from using the buff in area B. Then area B would be unbuffed while it counts down from the use in A. That would mean either leaving each area unbuffed for awhile each day or using other buffs from star to fill the gap. Neither is a good choice.
Instead only upgrade one to level 4 and stick the second off in a corner somewhere. The second one will just be a speed booster to cut the timer in half, allowing you to set off the next buff every time the first one wears off in the area you actually want buffed. (Area A every 12 hours)