No, you cannot access the same database from 2 different servers, unless you have DB2 PureScale (DB2 9.8). You can set up a shared disk system with 2 nodes for high availability, and point the applications to the second node if the first node goes down, usually by using a virtual IP address for the database that gets moved by a system administrator, who also starts DB2 on the other node when the first node is no longer available or DB2 is stopped on the first node. This is not used much anymore since the advent of HADR.
In addition to PureScale, there is DPF (Database Partitioning Feature) that "sort of" supports multiple node access, but that is more of a parallel database (or sharding) solution than what you are probably thinking of, since the database data is spread across the mutliple nodes and does not use shared disk for the data.