Duplicate all stored procedures with a new name
How about such a little script, to generate new scripts for all procedures, replacing all old names with new names (definition and calls):

SELECT 
    O.Name as ProcName 
    ,REPLACE(REPLACE(REPLACE(
        M.Definition, 
            'old_proc_name_1', 'new_proc_name_1'),
            'old_proc_name_2', 'new_proc_name_2'),
            'old_proc_name_3', 'new_proc_name_3')
        -- etc.
as CreateScript 
FROM sys.sql_modules as M INNER JOIN sys.objects as O 
ON M.object_id = O.object_id 
WHERE O.type = 'P'
and O.name not like 'sp%' -- exclude special system procs


Then you can execute all the scripts, either by hand, or using a cursor (more prefered for hundreds of procs).

But begin with checking carefully at least a couple of scripts before executing them.