In the first chapter of Death Stranding, Deadman says to Sam that he took his body fluids (blood?).
Deadman: During that time, we took the liberty of collecting fluid samples from you. You’re a repatriate. That makes you very special.
Then, in chapter 2, Sam asks Deadman to analyze his boots soaked in blood (he says he already took his blood). When Sam takes a shower, Heartman tells Sam that he will take his body fluids for him to test with the BTs.
Heartman: ... When you relieve yourself, a certain amount of chiral matter is flushed from your system. Chiral matter can adversely affect hormone secretion and nervous function. There’s a correlation between exposure and the development of phobias, as well as-in extreme cases-violent and suicidal impulses. Chiralium contamination has even been postulated as a trigger for the onset of DOOMS. Allow me to collect a sample of your excretions for my studies. They provide a non-invasive means to monitor your exposure to chirallum and your overall health.
If Deadman already took his bodily fluids in the prologue, why does Heartman needs his fluids again in chapter 2?