The problem with php Curl boundary

Friends, there is a problem:
uploaded image via curl on site and in the header is passed
Content-Type: Multipart/form-data; boundary=----------------------------bb9585680406

boundary – looks very strange (not properly generated) must be approximately boundary="158e2be9-fc4b-4bbc-ba9f-1754c6e38ee 9"

tried to manually add this header, that's what happened:
Content-Type: Multipart/form-data; boundary="158e2be9-fc4b-4bbc-ba9f-1754c6e38ee 9"; boundary=----------------------------bb9585680406

he still finished his in the end how to get rid of them?