How many times does a digital clock show the same digits at a time in a twenty-four hour period?

12 Times: AM - 1:11am, 2:22am, 3:33am, 4:44am, 5:55am, 11:11am

PM - 1:11pm, 2:22pm, 3:33pm, 4:44pm, 5:55pm, 11:11pm