I found some old libcaffe2.so and libcaffe2_test_dynamic.so in my /usr/local/lib. Once I got rid of them, as suggested, I could import torch successfully.
Regarding caffe2, I had to additionally protobuf (conda install -c anaconda protobuf) and future (conda install -c anaconda future). Now, I can execute successfully (from caffe2.python import workspace).
Thanks for all the help.