Exporting a workflow from the Broad Methods Repository to a workspace can occasionally result in the following error.

Error: Substream Source(EntitySource) cannot be materialized more than once

Our engineers are currently investigating this issue and working on a fix. As a workaround, if your workflow of interest is already in a Terra workspace, you can copy that workflow from the Workflows tab to the target workspace.

Retrying the export multiple times has also been reported to work.