Creating parts multiplies staff styles and may lead to crash

Context: commit 1cfa954 (2014-04-15) self-compiled on Linux Mint, Qt lib 5.1.0

Steps:

1. Create a score with several parts (the score is created with the 14 default staff types)
2. Do "File | Parts | Create | New All" (parts are created)

Result: With "Style | Staff types..." it can be seen that the score now has one additional set of 14 staff types for each part created.

Expected result: The score should keep its original set of staff types.

Notes:
The additional staff types seem attached to the staff of the parts. However, trying to modify these styles affects the part(s) in unexpected way (for instance, if number of lines is changed) and may ultimately lead to crash.