Answer:
Stays the same. 
Step-by-step explanation:
Density = mass/volume 
 
So if : 
 
M/V = D 
 
And if we were to double mass(M) and volume (V) 
 
2M/2V = D 
 
It will stay the same because the 2 and 2 would cancel out and we'd get the same density as the original value.