Several years back, we had a similar issue, where our title block did not look right in one drawing. It took a while to figure out why.
This one had me confused for a bit. Eventually, I tracked it down to the fact that our tech had not started a new drawing from a template, and then used Map or some such technique for pulling in the linework from the "others", the way he was taught. Instead, he took a drawing sent to us by "others", and started turning that drawing into his final product.
The problem cropped up when he inserted our title block. At the time this happened, we used a font called TITLE in our title block. It just so happens that the "others" also used a font called TITLE. When our tech inserted our title block into the drawing that was started by the "others", it used the "other's" version of the TITLE font.
After this little runaround, that particular tech finally realized why I tell them to always start a new drawing from our template. But I also went into our template and renamed all our fonts, so they now all include our company initials, and none of them use common names like TITLE anymore. This was similar to the problems that crop up from using fonts and styles named STANDARD, but was a bit more insidious...