Tap on Picture in MMS and a different picture opens up?
It is a known bug with the MMS in SOME LG smartphones where the older version of “Messages” app is installed. Previously deleted MMS picture shows up in newest incoming MMS message instead of the intended image due to this bug.

You can fix it by updating the "Messages" app to the latest version. 

Source: https://www.lg.com/ca_en/support/product-help/CT30014940-20150929584034