Sounds to me like a child's (his own or a sibling's) attempt at saying a long name like Max-Emanuel. Though it's more common that a child would find the sound p difficult and replace it with b. Replacing the bilabial consonant m with the bilabial p is unusual, but might be an idiosyncracy. Final -l is the diminutive in Bavarian dialect, but is here more likely the final l in Emanuel.
