Alphabet in an amino acid alignment changes on copy/paste

Scenario:

1. Open "_common_data/clustal/amino_from_wikipedia.aln".
   Expected state: it has the "Standard amino acid alphabet" (see the "General" OP tab).
2. Select (8; 1) (8; 3) rectangle.
3. Press Ctrl + C.
4. Press Ctrl + V.
   Expected state: the alphabet is "Standard amino acid"
   Current state: the alphabet is "Raw".