Hello,
If the urine is splitting in two streams, it can be due to congenital defects, scarring of the urethra due to STDs or other trauma, Obstruction, structural changes in lower urinary tract and prostatis. Passing of recurrent kidney stones can also cause scarring of the urethra and hence two streams of urine.
For evaluation of the same, I would suggest you to get it examined from a urologist and get an ultrasound and cystic urethrogram done to confirm the diagnosis.
I hope it helps. Take care and regards.