Yes, you can. However, we do not recommend using two providers for the same service. For example, you should not use two repricing service providers simultaneously, but your inventory management service should work normally with our Repricing Central or Feedback Central.
Having two service providers requesting same or similar data report at the same time will not only cause issues with adjusting price conflict, but may also put your MWS over its Throttling limit. Once you reached your request quota for your MWS account, Amazon will deny your request for essential data until the hourly quota is under control. In other words, it will affect the response time of our services.
Therefore, we recommend you to revoke MWS authorization for other service provider when you are ready to begin using our service.
You can find out more about MWS Throttling here: Throttling: Limits to how often you can submit requests
or check out Amazon's newest video on Throttling here: MWS: Throttling