Mishnayos Terumos Perek 5 Mishnah 8

עד שנפלה אחרת – another Seah of heave-offering/Terumah.

הרי זו אסורה – that it is like they fell at one time.

ור' שמעון מתיר – and it was known known to about first falling until it fell a second time, Rabbi Shimon admits that it is like the case when they fell at the same time. But he disputes where it was known to him in the meantime and he did not have the opportunity to lift it up until another fell, Rabbi Shimon holds that since he was about to lift it up is like something that has been lifted up, and he goes according to his reasoning , that he holds in general (Tractate Pesahim 13b; Tractate Bava Kamma 76b): He who is about to be sprinkled is considered as if it was sprinkled, but the Sages state that now, hoever, it was not lifted, and the Halakha is according to the Sages.