There are several things going on in your code. I suspect that what's really causing the problem is that you need to exit the interrupt handler before another interrupt callback can be triggered...but there is also a confusing mix of callback-based handlers and the GPIO.event_detected method.

I think you can simplify things by performing less manipulation of your interrupt configuration. Just have a state variable that starts at 0, increment it to 1 on the first interrupt, so the next time the interrupt method is called you know it's the second interrupt. No need to try setting multiple handlers like that.

Keeping in mind that I don't actually know what you're trying to do...I imagine something like this:

import RPi.GPIO as GPIO
import time

state = 0

GPIO.setmode(GPIO.BCM)
GPIO.setup(26, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(19, GPIO.IN, pull_up_down=GPIO.PUD_UP)


def interrupt_handler(channel):
    global state

    print("interrupt handler")

    if channel == 19:
        if state == 1:
            state = 0
            print("state reset by event on pin 19")
    elif channel == 26:
        if state == 0:
            state = 1
            print("state set by event on pin 26")


GPIO.add_event_detect(26, GPIO.RISING,
                      callback=interrupt_handler,
                      bouncetime=200)

GPIO.add_event_detect(19, GPIO.RISING,
                      callback=interrupt_handler,
                      bouncetime=200)


while (True):
    time.sleep(0)

From kernel gpio/sysfs.txt:

"value" ... reads as either 0 (low) or 1 (high). If the GPIO
  is configured as an output, this value may be written;
  any nonzero value is treated as high.

  If the pin can be configured as interrupt-generating interrupt
  and if it has been configured to generate interrupts (see the
  description of "edge"), you can poll(2) on that file and
  poll(2) will return whenever the interrupt was triggered. If
  you use poll(2), set the events POLLPRI and POLLERR. If you
  use select(2), set the file descriptor in exceptfds. After
  poll(2) returns, either lseek(2) to the beginning of the sysfs
  file and read the new value or close the file and re-open it
  to read the value.

"edge" ... reads as either "none", "rising", "falling", or
  "both". Write these strings to select the signal edge(s)
  that will make poll(2) on the "value" file return.

  This file exists only if the pin can be configured as an
  interrupt generating input pin.

The preferred way is usually to configure the interrupt with /sys/class/gpio/gpioN/edge and poll(2) for POLLPRI | POLLERR (important it's not POLLIN!) on /sys/class/gpio/gpioN/value. If your process is some "real-time" process that needs to handle the events in real time, consider decreasing it's niceness.

You can even find some example code on github that uses poll, ex. this repo.