Dropbox api conflicted copy

Using the 'update' mode and 'autorename:true' should result in the behavior you're looking for, if I understand correctly.

Here's a contrived example:

var filePath = '/test_324605.txt';

// gettting the current metadata for a file:
dbx.filesGetMetadata({path: filePath})
  .then(function(response) {
    console.log("got filesGetMetadata response:");
    console.log(response);

    // saving the current rev for the file:
    var rev = response['rev'];

    // simulating the "first" persion to upload a new version
    dbx.filesUpload({path: filePath, mode: {'.tag': 'update', 'update': rev}, autorename: true, contents: "some new data"})
      .then(function(response) {
        console.log("got first filesUpload response:");
        // this should show the existing file updated in place:
        console.log(response);

        // simulating the "second" person to upload a new version, but using the original rev
        dbx.filesUpload({path: filePath, mode: {'.tag': 'update', 'update': rev}, autorename: true, contents: "some different data"})
          .then(function(response) {
            console.log("got second filesUpload response:");
            // this should show the new version as a conflicted copy:
            console.log(response);
          })
          .catch(function(error) {
            console.log("got second filesUpload error:");
            console.error(error);
          });

      })
      .catch(function(error) {
        console.log("got first filesUpload error:");
        console.error(error);
      });


  })
  .catch(function(error) {
    console.log("got filesGetMetadata error:");
    console.log(error);
  });

Running that, I do get the following output:

got filesGetMetadata response:
{.tag: "file", name: "test_324605.txt", path_lower: "/test_324605.txt", path_display: "/test_324605.txt", id: "id:25N5ksooX-sAAAAAAAM5rw", …}

got first filesUpload response:
{name: "test_324605.txt", path_lower: "/test_324605.txt", path_display: "/test_324605.txt", id: "id:25N5ksooX-sAAAAAAAM5rw", client_modified: "2019-01-23T16:20:57Z", …}

got second filesUpload response:
{name: "test_324605 (API Test Account's conflicted copy).txt", path_lower: "/test_324605 (api test account's conflicted copy).txt", path_display: "/test_324605 (API Test Account's conflicted copy).txt", id: "id:25N5ksooX-sAAAAAAAM5sA", client_modified: "2019-01-23T16:20:59Z", …}

The first upload updates the existing file, and the second one results in a conflicted copy.

If something isn't working as expected for you, please share the relevant code and output.