Cataclysm Clear my doubt on combustion pls

[zenoanand55]

guys i have a doubt, i made a crit with FB with 13475 damage(crit) there was 2 ignite ticks for 3557 ticks easch, now when i combust, as per its says combustion must make a damage per time equal too sum of all combined effects. Here i had ticks of ignite for 3557 and 3557, so my combustion must tick at 3557 too but its ticking only at 1778(half of the periodic damage happening to the dummy) any idea about this would be welcomed...

[Heimdal]

Because ignite ticks two times, if your ignite damage started as 5000, wit would tick two times for 2500 each, if you let it tick once, there will only be 2500 damage left on that dot