Library name is not unique: two different paths, one has 'extras/'

I have imported the projects: DISCO-F746NG_AUDIO_demo and DISCO-F746NG_LCD_demo

I get each time this kind of error (for many different library names, each time I restart the build appears another one):

Build started
Using toolchain ARMC6 profile {'ENV': {'ARMLMD_LICENSE_FILE': '8224@10.100.158.60:8224@10.100.125.150'}, 'PATHS': {'ARMC6_PATH': '/opt/ARMCompiler6.15.13/bin/', 'ARM_PATH': '/opt/armcc5_06_u6/'}, 'common': ['-c', '--gnu', '-O3', '-Otime', '--split_sections', '--apcs=interwork'], 'cxx': ['--cpp', '--no_rtti'], 'COMPILE_C_AS_CPP': False, 'NEW_SCAN_RESOURCES': True}
scan /tmp/chroots/ch-1d61af4e-2aca-48fe-a24b-57260762ca26/src
scan /tmp/chroots/ch-1d61af4e-2aca-48fe-a24b-57260762ca26/extras/mbed-os.lib
Library name 'events' is not unique (defined in '/tmp/chroots/ch-1d61af4e-2aca-48fe-a24b-57260762ca26/extras/mbed-os.lib/events/mbed_lib.json' and '/tmp/chroots/ch-1d61af4e-2aca-48fe-a24b-57260762ca26/src/mbed-os/events/mbed_lib.json')
Internal error.
Build failed

What can I do in order to fix it?