That’s a recipe for denial. They will see it as a sign of desperation. So, I’ll suggest that the person sticks to one application, EB or MB.

I guess it depends upon at what stage each of your application is. secondly, At the time of AOS, you can refer only one application. hope this helps. I too had 2 greencard applications but both were Employment based. I used only one that had current PD. hope this helps

can the person file another application immediately if one application is denied for whatever reasons?

@Saad yes you can file another application if one is denied

file the employment base, the marriage takes longer

i have seen people filing such that both are pending. usually if one is granted then the other one gets closed. Talk to lawyer but don't think there is any law that prevents it.