As reported by Kikar, A frum, Haredi, man found himself in a faraway land with no Jews. The beginning of this sounds like the start of a fairy tale.. Anyways, the traveler came across a local Jew - the local was happy to see another Jew and asked to borrow his tefillin and lay them each day the traveler was in town.
When it was time for traveler to leave and head back home, Mr Local Jew made a somewhat difficult request of his new Jewish friend - he asked if he would mind leaving his tefillin behind, for him to keep, and Mr Traveler would be able to replace them with a new pair when arriving back home in Israel. Mr Local Jew has no tefillin and has no way to get a pair, but Mr Traveler could easily get a new pair when he gets back home...
Mr Traveler thought about and happily decided to leave his tefillin for Mr Local Jew. When he got back home, he bought himself a new set.
After the fact, Mr Traveler asked a number of rabbonim if what he had done was correct and proper or if it was wrong - because he left his tefillin behind for Mr Local Jew he had to go a couple of days without laying tefillin until he could replace them! Maybe he was wrong for doing so.
The question was brought to Rav Chaim Kanievsky who said that what he did was proper, but he needs to make up for the days he did not lay tefillin by laying his tefillin twice per day, once at the morning Shacharis services and once at the afternoon Mincha services, to make up for the days he missed. Other rabbonim the question was presented to agreed with this response.
Rafi, the blogger there, notes that:
The whole story ad [sic] discussion is interesting, but what is most interesting, to me, is the idea that because he missed a few days of laying tefillin he has to lay tefillin twice a day for a few days to make up for it. I don't think I ever heard that before.
My question is, where in any Halachic literature is there a precedent for this suggestion, where we are told that someone who missed a day of tefillin should make it up in this fashion? (Note that it is possible that this is his own chiddush, and that there is no precedent.)