Answer:
The force will double
Step-by-step explanation:
The electrostatic force between two electric charge is given by Coulomb's law:

where
k is the Coulomb's constant
q1 and q2 are the two charges
r is the separation between the charges
In this problem, at the beginning the two charges are equal, so
q1 = q2 = q
and the force between them is

Later, one of the two charges is doubled in magnitude:

So the new force will be

so, the force has doubled.