The Open Font License and Reserved Font Names

Preventing collisions is important. Most applications identify fonts only by their names. They have no ability to identify or use multiple versions of a font with the same name.

Tiny modifications to the spacing, kerning, or any of the vertical metrics of a font will cause documents to re-flow and cause things like page number references get messed up. Illustrations may end up in the wrong places, and so on.

Also suppose there a font supporting multiple scripts (e.g. Roman, Cyrillic and Greek)- then someone makes a derived version eliminating one of those scripts because they don't need it and want to save space - but they keep the same font name for the new version. Then you have a newer version floating around with less utility that the first. Since you cannot install two fonts with the same name, a document created with the earlier version may no longer show a whole range of characters if the newer version is installed.

As long as there is no other way for applications to identify fonts, use of the same name in different versions and derivatives needs to be carefully controlled. The only practical way of doing that is to leave font names in the control of the font developer who first used it.