In Parashat Tzav – G-d says
“…in the place you slaughter the Olah offering, slaughter the Sin offering … ” (Vayikra / Leviticus 6:18)

One reason this is done is to save the person bringing the Sin offering from embarrassment, So people won’t know what kind of offering a person brought. We should respect people’s feelings & give people leeway to allow them to save face.