[Scons-users] how to properly share an output folder with two subfolders?

[daggs]

Greetings,

I have this tree:
root
├── output
├── SConstruct
├── a
│   └── SCpnscript
└── b
    └── SCpnscript

in SConstruct I do this:
env = Environment(O = Dir(env.subst('#/output')).abspath))
SConscript('a/SConscript', variant_dir=env['O'], duplicate = 0, exports = 'env')
SConscript('b/SConscript', variant_dir=env['O'], duplicate = 0, exports = 'env')

when I run scons, I get this error: scons: *** 'output' already has a source directory: 'a'.
I tried duplicate = 1 for both but it didn't worked.
if I change SConscript('b/SConscript', variant_dir=env['O'], duplicate = 0, exports = 'env')
to SConscript('b/SConscript', exports = 'env') it works but I'm not sure that is the proper way to do it.
so I wonder, what is the proper way to instruct both them to SConscript to one output folder?

Thanks,

Dagg.