Back in '84, I visited Banjul Tower. The controller complained how busy they were getting, with 34 movements planned for that WEEK. He had 7 scheduled for that day!
He had two frequencies, one for approach and one for tower. Although he could receive on both simultaneously, he could only select one transmitter, which had to be deselected before he could select the other.
An inbound called; he had the wrong Tx selected; by the time he had de-selected and re-selected, the inbound had called on the other frequency. When he finally got two-way contact, he got the callsign mixed up with another aircraft for which he had an estimate!