Tandem feeding with newborn

Hello mommies! My first born is now 1year & 9months old and my newborn is 6days old. Nagtandem feeding sila and i am just curious kasi baka yung colostrum na for my newborn ay yung panganay ko na nkakakuha. Possible po kaya sya? Ngstart po ako mgtandem fed nung 3days old si baby. I just notice dn po na yung left boob ko(boob na dinedede ng newborn ko) ay natural color ng milk lumalabas tapos sa right boob(dito nman dumedede yung panganay ko) medyo yellowish sya.