Q. Is there a source for the strange minhag that some have to say shnaim mikro and once targum on Parshas Vaeschanan, while wearing taalis and tefilin?

A. Indeed, there are those who quote that the Chasam Sofer would keep that minhag, since one reads in Vaeschanan, the parsha of shema which mentions the mitzva of tefilin. Shulchan Aruch (O.H. 25: 4) rules that one should not read the shema without donning tefilin, as he appears to be testifying falsely by his own actions (Brochos 14, See Nitei Gavriel – Bein Hametzarim 96: 4).
Horav Shlomo Miller’s Shlit’a opinion is that on should keep the traditions of his family and community, and not add minhagim and new traditions without need.

Rabbi A. Bartfeld as advised by Horav Shlomo Miller Shlit’a