Maven choose the wrong transitive dependency

I have a dependency used by 2 sub-projects (spring-core) but with 2 different versions (2.5.5 and 2.5.6.SEC01)
My project which uses theses 2 sub-projects gets spring-core 2.5.5 instead of the more recent 2.5.6.SEC01

I attach a test project which illustrates this case.
To reproduce:
1. untar proj.tar.gz
2. Run ./build.sh
3. Have a look at the xxx-tree.log generated files

The dep for apireg is 2.5.5 -> OK
The dep for rcpers-core is 2.5.6.SEC01 -> OK
The dep for adam-services is 2.5.5 -> NOK (Should be 2.5.6.SEC01 since it depends on rcpers-core)