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)?
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