A stationary unstable neutral particle decays into 2 separate particles with equal mass and velocity, what might the resulting bubble chamber diagram look like?

The two decayed particles will form identical spirals but in the opposite direction to one another, as they will have to be oppositely charged to preserve the overall charge. The spiral patterns will be identical as the two particles will have equal momentum, overall momentum is still unchanged as the vector sum of the two particle's momenta will still be zero.