Having a car accident while driving and two people dying
If the reality is as you mentioned, that you are found 25% at fault of the accident, then you must make two Kaffarahs for the involuntary manslaughter. They are: to free two Muslim slaves and if you can not afford this, to fast for four months; each two month must be consecutive. Allah (Exalted be He) says:
...and whosoever kills a believer by mistake, (it is ordained that) he must set free a believing slave and a compensation (blood-money, i.e. Diya) be given to the deceased’s family
And whoso finds this (the penance of freeing a slave) beyond his means, he must fast for two consecutive months in order to seek repentance from Allâh. And Allâh is Ever All-Knowing, All-Wise.
You were charged with having a part in involuntary manslaughter of two Muslims, so you must make the Kaffarah for killing both persons.
The Kaffarah for involuntary manslaughter multiplies based on the number of the persons killed, just as Diyah, since each person killed is a separate individual without any bearing on the other.In addition, there is no sin on you for delaying making Kaffarah for this period. You should hasten to make it in order to free yourself from the burden, unless you have an excuse.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.