In the future, the Pinehead brothers appear not to have aged; on the other hand, Captain Planet obviously has though he is never supposed to age (his appearance from the far future in "Future Shock" confirms this).
Both the present and future versions of Kwame's Earth rings light up during the summoning when only one was used to summon Captain Planet (one ray brought him, not both). Even if only one really did bring him, they should not both have been taken out of the rings with Captain Planet using it to reroute the pursuing truck a few minutes later.
In the future, the Pinehead brothers appear not to have aged; on the other hand, Captain Planet obviously has though he is never supposed to age (his appearance from the far future in "Future Shock" confirms this).