Q. Is it permitted to go out on Shabbos with two masks, one for me and one for my friend whose Rav does not allow him to go out with a mask on Shabbos but will be attending a shul where they require it?
A. Horav Shlomo Miller’s Shlit’a opinion is that one should avoid wearing two masks simultaneously, just for the purpose of taking it to shul on behalf of someone that does not wear it where there is no eruv. This is due that it is unusual and unnecessary to do so and is therefore not considered a ‘malbush’ or a piece of clothing one can wear in a public domain during Shabbos, as explained in question 2640.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit’a