Mxnet error when running in parallel

[Maelstrom2014]

during getting embeddings in face_embeds = face_feature_extractor.get_face_feature_batch(np.array(all_aligned_img))

c:\jenkins\workspace\mxnet-tag\mxnet\src\operator\tensor../elemwise_op_common.h:135: Check failed: assign(&dattr, vec.at(i)): Incompatible attr in node at 0-th output: expected [18,3,112,112], got [24,3,112,112]

What I'm doing wrong? This error is not repeatable (happens in different time), so I think it causes tha mxnet using the same memory in different threads.