Garudapurana 3.12.64

3.12.64

rāmakṛṣṇādirūpeṣu antarasya vicintanam /
rāmakṛṣṇādirūpeṣu parājayavicintanam //

thinking of a difference among forms such as Rāma and Kṛṣṇa;
thinking of defeat among forms such as Rāma and Kṛṣṇa;