I dont think the 2 year old would have to pay so thats one plus.
A lot of the jokes might get lost on the 5 year old, but he/she would still enjoy it over all.
Probably a perfect time to go, otherwise you would technically have to pay for the younger child in the future, and it may be 2 or 3 years until the 2 year old can appreciate it enough to justify the cost.
(This is assuming 2 and under is no cost)