CC Madhya 21.60
dvārī āsi’ brahmāre puche āra bāra
“When Kṛṣṇa was so informed, He immediately asked the doorman, ‘Which Brahmā? What is his name?’ The doorman therefore returned and questioned Lord Brahmā.
From this verse we can understand that Brahmā is the name of the post and that the person occupying the post has a particular name also. From the Bhagavad-gītā: imaṁ vivasvate yogam. Vivasvān is the name of the present predominating deity of the sun. He is generally called Sūrya, the sun-god, but he also has his own particular name. The governor of the state is generally called rāja-pāla, but he also has his own individual name. Since there are hundreds and thousands of Brahmās with different names, Kṛṣṇa wanted to know which of them had come to see Him.