Hi @ares , I understand that you need to connect two different Express Route circuits from two provider to the same Express Route Gateway.
Answer for your question: Yes. An ExpressRoute circuit represents a logical connection between your on-premises infrastructure and Microsoft cloud services through a connectivity provider. You can have multiple ExpressRoute circuits. Each circuit can be in the same or different regions, and can be connected to your premises through different connectivity providers.
Please make sure that your Express Route Gateway SKU is sized correctly based on their max number of Circuit connections.