I know two brothers who will buried next to each other--with their wives on the "outside." One may be tempted to conclude that the brothers purchased their cemetery plots the same day, but they did not. Be careful not to infer information that is not stated in the records. Adjacent burials mean that the burials are adjacent. The brothers could have purchased their plots the same day or one different ones.
The dates in this example aren't really key to any research conclusions, but sometimes we assume facts that are not in evidence. And sometimes assuming those facts hinders further research efforts--in addition to being plain wrong.