[Bug] Resnet18 export does not work anymore

Context

Following the recent changes, the Resnet18 export script returns an error.

Test

Inside aidge_export_cpp/examples/export_ResNet18/ :

resnet18.py --mock_db

Error :

line 64, in export.py
    aidge_core.expand_metaops(model, recursive=True)
RuntimeError: unknown or duplicate input: _Conv2D_resnetv15_stage4_conv3_fwd (of type Conv2D)