Tyres 91V and 94Y can be mixed???

Hello, I have on my CL203 two summer tires Goodyear Asymetric II 225/45/17 94Y. Now I get for 95€ per piece 2 new Asymetric II but as 91V version. Can I take the safe and which one I should do at the front and which one on the rear. Since the Mercedes rear wheel drive is, it is advisable to take the 94Y or it just doesn’t matter. Thanks for your help.