To determine which switch corresponds to each bulb with only one entry into the room, follow these steps:
Turn on the first switch and leave it on for a few minutes.
After some time, turn off the first switch and turn on the second switch.
Enter the room with the light bulbs.
Now, you have three possible scenarios:
The bulb that is on corresponds to the second switch.
The bulb that is off but warm corresponds to the first switch (as it was on initially).
The bulb that is off and cool corresponds to the third switch (as it was never turned on).
This method allows you to identify which switch controls each bulb using only one entry into the room with the bulbs.