Possible bug when requesting with the same parameters and different handling of the authentication key to a simulated api

I I was sending a request with this url https://my.api.mockaroo.com/users/456?key=123xxx by postman and also with this url https://my.api.mockaroo.com/users/456 and sending the key parameter as part of the header with the same value 123xxx and despite sending the same id 456 I am getting a different result. My script handles a cache for the response. I think both techniques should have the same response.