What do you think these mystery marks could be?

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These are pictures of my friend's bedroom carpet. She said these roundish stains have appeared quite mysteriously, and they have her baffled. I have to admit, they are the strangest stains I've ever come across. I haven't seen them in person (may do so this week) but based on her description she said they're more 'discolorations' than anything else. Any insight would be appreciated!
q what do you think this could be, cleaning tips, flooring
q what do you think this could be, cleaning tips, flooring
  30 answers
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