No, it's not possible for two service providers to use the same VLAN. Each provider requires a unique VLAN to ensure proper network segmentation and avoid conflicts.
Provisioning Configuration
VLANs are entered in the Provisioning configuration that could be found in the Settings menu. The most common configuration is to give a service provider one Network Service (VLAN).
Changes of the provisioning configuration should only be performed by someone with total insight to the network. Any mistake can have a significant impact on the network services.