3D Text has a font family feature which has existed since blender was open sourced.
I think this is a fairly obscure feature, to figure how to use It I ended up having to check the source code, I'll attach an example file.
While checking the code I noticed some limitations which IMHO should be fixed, unless the feature gets removed.
- No unicode support (only ascii characters).
- Max name length was never updated (still 23 chars).
- Tooltip is wrong (suggests 'family_a' whereas 'familya' is needed).
- Recursive dupli's dont work.
- Character rotation isnt supported.
- Object rotation is ignored (maybe this is best? - but this isn't how dupli-verts work elsewhere).