Not every anomaly contains a hidden message.
Occam's Razor… the conclusion that requires the fewest assumptions is likely the truth.
4 new devices.
1 new one for the original Q, so no letter designation.
3 other new ones for 3 other individuals who are NOT the one we've been talking with the whole time.
This means 3 other people who are probably not so careful in what they type and how they type it.
So two of them typed "test", and one typed "Test"… likely purely innocent.
In medicine, when diagnosing a disease, you look at the symptoms and come to a rational conclusion (think Dr. House)… there's a saying in the medical community. "When you hear hooves galloping, you assume it's horses, not zebras."
Yes, sometimes it's zebras, but most of the time it's horses.