Different people may create the classes at different times. (People may forget to explore the existing classes before adding more.) Occasionally, you'll find people doing this intentionally (but misguidedly) so they can distinguish the names.
What to Do
Pick the best name, and use Rename Method (or field, constant, etc.) to give the same name to the same things. Once you've done this, you may find that some classes appear to be more similar than they did before. Look for a duplication smell and eliminate it.
Improve communication. May expose duplication.
The Eiffel language uses a common pool of words for the names of its library features. You can use this technique as inspiration: Look to existing library names for the vocabulary you use.