As far as I know, if you request a score report to send to the same institution within 2-3 months, you may write on the score report request form that it is duplicate. Then, you won't be charged. If it is the free service that ETS is supposed to send it for free, ETS must do it. Please allow about 2 weeks for the score report to reach the destination.
Any request services that you have ETS do for you, if ETS does not do it, you may send a new request and put , "Duplicate". You won't be recharged.
Knok