What are trigger scriptlets and how they can be used during rpmbuild?

Issue

• What are trigger scriptlets and how they can be used during rpmbuild?
• There is some problem with trigger handling.
• Let's analyze the example below: There is a sub package named test-test in the version 0.9-20
• We have 2 triggers:

1)
%triggerin -n test-test -- test-test < 0.9-23
echo "triggerin TEST-TEST < 0.9-23"

2)
%triggerin -n test-test -- test-test < 0.9-22
echo "triggerin TEST-TEST < 0.9-22"

• Scenario 1: Trigger 1 is before the trigger 2 in the test.spec file

rpm -Uvh test-test-0.9-23.rpm

Preparing...                ########################################### [100%]
   1:test-test              ########################################### [ 50%]
triggerin TEST-TEST < 0.9-23

• Scenario 2: Trigger 2 is before the trigger 1 in the test.spec file

rpm -Uvh test-test-0.9-23.rpm

Preparing...                ########################################### [100%]
   1:test-test              ########################################### [ 50%]
triggerin TEST-TEST < 0.9-22

• Why only one trigger is executed ?