While building BizTalk projects within Visual Studio, it is possible to receiving the following error when trying to compile a project with multiple orchestrations:
“The namespace ‘[namespace]’ already contains a definition for ‘_MODULE_PROXY_'”
While the error seems obvious, in my case, the namespaces were indeed unique, such that the above error did not make much sense. The underlying issue was in fact that the type names of two of the orchestrations within the project were identical. It turns out that an orchestration was at one point duplicated, and only the namespace was changed. After making the type names unique, the project successfully compiled and deployed.