For a VHDL project, the ipif_pkg does not include the Component Name as a prefix.
This could cause package name conflicts between multiple cores in a single design.
If using the core .xci file in the Vivado tool, this issue is only seen if you are using multiple instantiations with different configurations.
If using the core in IPI, the conflict could be seen if you are using multiple instantiations regardless of the configuration.
In the following files "ipif_pkg" should be replaced with <component_name>_ipif_pkg.vhd:
This has been addressed in the v7.0 (Rev1) update (see (Xilinx Answer 57446)) and will also be addressed in the v8.0 core scheduled to be released in Vivado Design Suite 2013.3.