The Meiri Berachot 21 (Peri Hadash, Keneset HaGedola and others) writes that in a case of Safek Deorayta Lehumra where one isn't certain after performing the action that he has fulfulled his obligation (i.e. Techelet) he still must perform the action. I know the Bet HaLevi argues with this. Who else is on the Bet HaLevi's side (if anyone)?
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The Maharam Shif says it in Bava Metzia 6b. (Other Rishonim there who don't answer like him presumably argue. For others who argue, see Rav Schechter's Ginas Egoz.)
I don't remember the Meiri saying more than what the Chavos Daas says but the din safek deoraysa lchumre clearly applies here as is muchach from Mishna berura Siman 32:50, 33:5 and in Biur halacha ד"ה אין and MB 39:26 and Biur halacha in 648 ד"ה שדומה (page 136) also the biur hagra on 32- 5 is mevour like that there is an entire sefer dedicated to this on otzar hachochma called mishmeres mitzvah it can be found here