SQL Server: Why would i add “;1” to the end of a stored procedure name?

Question

i came across a compatibility issue today, as a customer upgraded from Windows XP to Windows 7.

The (12 year old code) is calling a stored procedure on the SQL Serve

Answer 1

see CREATE PROCEDURE (Transact-SQL) SQL Server 2008 documentation

--Transact-SQL Stored Procedure Syntax
CREATE { PROC | PROCEDURE } [schema_name.] procedure_name            [ ; number ]  <<<<<<
    [ { @parameter [ type_schema_name. ] data_type } 
        [ VARYING ] [ = default ] [ OUT | OUTPUT ] [READONLY]
    ] [ ,...n ] 
[ WITH  [ ,...n ] ]
[ FOR REPLICATION ] 
AS { [ BEGIN ] sql_statement [;] [ ...n ] [ END ] }
[;]

 ::= 
    [ ENCRYPTION ]
    [ RECOMPILE ]
    [ EXECUTE AS Clause ]

;number

An optional integer that is used to group procedures of the same name. These grouped procedures can be dropped together by using one DROP PROCEDURE statement.

Note:

This feature will be removed in a future version of Microsoft SQL Server.
    Avoid using this feature in new development work, and plan to
    modify applications that currently use this feature.

Numbered procedures cannot use the xml or CLR user-defined types and cannot be used in a plan guide.

you can use this system view to find all of these and begin to rewrite them as separate procedures:

sys.numbered_procedures (Transact-SQL)