Yes. Whatever mixture is in the pills, it doesn't contain any primary or secondary amine - e.g. MDA or MDMA,
i.e. if the amine test results are reliable (buffer added, age of reagents, etc.)
Many compounds can produce a dark red-purple-black reaction product with Marquis. Thay is why it's good to have another reagent like Mandelin or Mecke on hand to back up the Marquis result.