If one is wearing techeiles strings on his tallis katan, and goes up to be shliach tzibbur (lead the prayer), may he put on a shul tallis (prayer shawl) that is non-techeiles, i.e., all white strings? The reverse works as well (someone wearing all white strings puts on a garment with techeiles strings).
The reason I think it may be not allowed is due to the issue of tarti d'sasri, meaning a mutual contradiction.