Contained Databases use TempDB Collation for Temporary Stored Procedure names instead of CATALOG_DEFAULT
Meta-data (mainly name resolution) for temporary objects created within a Contained Database is supposed to follow the Collation rules of CATALOG_DEFAULT (i.e. Latin1_General_100_CI_AS_KS_WS_SC ). And this is the case for Temporary Tables, Table Variables, and even Indexes on Temporary Tables.
But, meta-data for Temporary Stored Procedures (i.e. their names) is not using the CATALOG_DEFAULT Collation, but instead is using the Instance / Server / tempdb Collation, which is expected behavior for Non-Contained Databases.
I have tested this on SQL Server 2012 SP4, and SQL Server 2016 SP1.
Solomon Rutzky commented