Joel_Jantsen, nutildah, suchmoon thanks for your responses. You all are right. I agree with you. There is no evidence and we cannot accuse users above.
This kind of merit "return" happens quite often and the original senders don't really have control over this, do they?
No they don't.
Even before making this post, I expected these responses from trusted members of the forum and I know that there is no evidence.
TBH, I wanted to post this topic 2-3 days ago. But I didn't, because there was no evidence of abuse and even now there isn't.
Today, I checked the account in question again and saw that a same thing is happening again and again.
Even until the last moment before posting this topic, I was hesitant about making this post.
If you check the merit history of
bitcoinermatt, you will see that he has sent merit to 6 users in 9 merit transactions.
All those 6 users has sent back merit to
bitcoinermatt immediately after they received merit from him.
You are right that some newbies think that merit is something like thank you. But it's a bit suspicious, if you merit 6 users and all of them think in that way and merit you once you merit them.