default or selected kernelversion does not have config value CONFIG_STMMAC_DUAL_MAC.
Result is shown for kernelversion 6.2.5

STMMAC: dual mac support (EXPERIMENTAL)

configname: CONFIG_STMMAC_DUAL_MAC

Linux Kernel Configuration
└─>Device Drivers
└─>Network device support
└─>Ethernet (1000 Mbit)
└─>STMMAC: dual mac support (EXPERIMENTAL)
In linux kernel since version 2.6.32 (release Date: 2009-12-02)  
Some ST SoCs (for example the stx7141 and stx7200c2) have two
Ethernet Controllers. This option turns on the second Ethernet
device on this kind of platforms.