You could even achieve that with one report. Let's take a webkit report example (same princple can be aplied to rml reports): If you need two different layouts:

Add a boolean field for the object, and then in report, make a condition:

if object.my_boolean:
    $object.this}
else:
    ${object.that}

If two options is not enough, you can use selection field, and apply conditions for each selection;

if object.selection == 'this':
    ${object.this}
elif object.selection == 'that':
    ${object.that}
elif object.selection == 'something else':
    ${object.something_else}

You can actually put under such condition anything you like- not only tags, but html elements also.

Hello

It's possible to have multiple reports for one model. You can develop one report for every layout you need.

AJ