You will have to be more specific about your workflow. CaptureOne has a few different ways to pass image files to another application.
1) Edit with ...
2) Open with ...
"Edit with..." will render the raw file into an RGB image file (like a TIFF or JPEG) with the CaptureOne settings applied and pass that rendered file to the application of your choice.
"Open with..." will simply pass the raw file to the application of your choice, without any CaptureOne edits applied.
When you bring your images into CaptureOne, it will render the previews that you see according to whatever the default settings are (for example, it will choose the camera's ICC profile and the Auto curve type, the As Shot white balance, etc.). It will then create a preview of the raw file according to these settings.
If you "Edit with..." then CaptureOne will apply these settings and make a TIFF or JPEG that looks like the CaptureOne preview and pass it to DxO.
If you "Open with..." then CaptureOne just passes the raw file to DxO, with no edits applied.
When the passed file comes into DxO:
The "Edit with..." TIFF or JPEG will look like the CaptureOne preview because CaptureOne made the TIFF or JPEG with the CaptureOne settings.
The "Open with..." image will be DxO's raw preview rendering, according to all of the default settings and automagic stuff that it does to a raw file from your camera.
This is probably where your difference is coming from, but without more info, it is not possible to pinpoint the root of what you are describing.
See this thread:
https://photography-on-the.net …showthread.php?p=19004952
for a workflow description related to CaptureOne and DxO and using CaptureOne to pass the raw file to DxO for NR and lens correction and then passing the resulting DNG from DxO back to CaptureOne. If you really like the CaptureOne colors or editing tools, but require the DxO NR, then you probably want to choose files in CaptureOne, use the "Open with..." command to send the raw files to DxO, do the NR there, and export DNGs (they will be linear DNGs [demosaicked] so that the pixel operations of NR can be applied to the data) back to CaptureOne for further editing.
Kirk