Many tokens exist on several chains. They share a ticker but have their own address per chain, which is why they appear as separate rows in the holdings list. That is correct: technically they are different tokens, economically they are the same one.

The same token on other chains block makes that connection visible. The link is made solely through the token's market identifier, not through the ticker: two tokens both called "USDT" without a shared identifier are not merged. A matching name alone is no proof.

The foreign addresses listed have not been checked and hold no balance of this wallet. They only show under which address the same token is listed on the respective chain.

Note the difference to the block above: contract detection talks about one address across several chains, this block talks about several different addresses that denote the same token.