This isn't such a big deal, Victor.
If the frame has had the bosses added retrospectively, then it is likely that they will have been silver-solderd into place. Most even half -decent builders would use silver.
However whether they are fixed with silver or silicon-bronze brazing rod they are easy to remove with the judicious application of a little very local heat. Otherwise the bosses can simply, but carefully, be filed off - either way you are left with two holes that need to be filled.
Filling the holes can be effected in several ways of which the most simple is to choose a pair of short soft iron rivets with more or less the same diameter shank as the holes to be filled. The rivets are silver-soldered into place, the heads carefully filed off, and linished to a fine finish preferably with a hand-held fine emery or aluminium oxide strop. If rivets are not readily available, cheese or dome headed bolts will do. All that should show of the solder/brass is too fine circular lines..
Another way is more fiddly, adds fewer grams to the job - depending of course on the length of the shank of the rivet -but can result in two full silver/brass circles. The problem with this method is that the larger areas of solder may be eroded more than the surrounding steel if the frame has to be sand-blasted at any later time, leading to very slight "hollowing"
Anyhow ..that's how I have filled up those holes for years...but there must be many more solutions out there on the List