Biometrics for I-551 and I-131

I have entered recently in US as an LPR.

I have had my biometrics appointment for I-551 just this month and I have also sent I-131 because I will have to live abroad for studies. One of the requirements of I-131 is to have biometrics done, but since I have done it for I-551 do I have to do it again for I-131?

I have read somewhere that biometrics is generally valid for 15 months so if I have a biometrics requirement for two different applications and if I have done it once do I have to do it again? Do they re-use it or will ask for the fresh once every time within 3 months?

USCIS may reuse biometric within 15 months of the most recent collection. If they need again for any pending application, they will send biometric appointment letter.