Inferring DP-ROM

Quartus can only infer logic, that can be realized by the existing hardware. A read enable isn't present in the RAM/ROM hardware, so Quartus has to use an equivalent construct. It is apparently not operational with a DP variant. You can try to find another way compatible with your intended use. It's general helpful to understand the available hardware options, particularly wich signals have to registered. The information is present either in the alt_ram MegaFunction user guide or the respective hardware manual.