If two files have blocks named the same thing, compiling them redeclares the block twice in the output.
Jemplate.templateMap['block'] = function(context) { // I am from bob.tt!
...
Jemplate.templateMap['block'] = function(context) { // I am from cow.tt!
So if you have two files each with a block named 'block', and you render a template that uses that block, you have no idea which one you are going to get! Sadness.