Thank you very much.
Unfortunately, "equal pay" laws only prohibit employers from paying employees differently if the reason for the difference in pay is a legally protected trait, such as gender, race or religion. No law requires employers to be generally fair or to treat all employees the same. Therefore, no law would prohibit your employer from unfairly classifying you as an MRI Technologist 1, even if they are doing this strictly to justify paying you less and you are performing the exactly same tasks as an MRI Technologist 2. Again, it's not fair, but the law does not require your employer to be fair, the law only prohibits your employer from paying you less because of a legally protected trait such as your gender race or religion.
So, I'm afraid all you can do here is attempt to reason with your employer and appeal your classification with HR. Ultimately, though, if your employer is not responsive to your complaints you would not have any legal remedies, and your only options would be to accept the terms of employment being offered to you or leave for better employment where you are treated more fairly.
I hope that you find this information helpful and am genuinely sorry if it is not what you were hoping to hear. Please do not hesitate to let me know if you have any questions or concerns regarding the above and I will be more than happy to assist you further.
If you do not require any further assistance, please be so kind as to provide a positive rating of my service so that I may receive credit for assisting you. Very best wishes moving forward.