Is it possible for multiple accounts to use a single API ID to make calls simultaneously?

Is it possible for multiple accounts to use a single API ID to make calls simultaneously?

Yes, it is possible, but not recommended, as call limits are set at the APPID level, not at the platform account level.
Multiple accounts share call quotas and limits
● Default limits for all standard API calls
Maximum number of requests per 10 seconds for a single OpenAPI account: 300
● Call limits for device control interfaces (3.7 interfaces)
Maximum number of requests per minute from a single OpenAPI account: 50