Hey @Tim_Larson,
Welcome to the community. It really depends upon what you are looking to get out of the courses. If you have a strong grasp on the Machine Learning basics, and if you are looking to enhance your Tensorflow skills, your current course might be more suitable.But if you are looking to strengthen your hold on ML basics or want to review them, then pursuing Machine Learning Specialization might be a good choice.
Moreover, there’s nothing stopping you from completing your ongoing course first, and then pursue MLS. A similar post discussing the similarities and differences between Deep Learning Specialization and Machine Learning Specialization can be found here. I have just mentioned this for your reference.
Lastly, if you are still feeling confused, you can always audit the courses, and if they fit your needs, then you can proceed with your subscription. I hope this helps.
Regards,
Elemento