If you only want to run the failed tests, don't tell prove to run anything else:

$ prove --state=failed 
t/02.t .. 1/1 
#   Failed test 'B'
#   at t/02.t line 2.
# Looks like you failed 1 test of 1.
t/02.t .. Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/1 subtests 
t/04.t .. 1/1 
#   Failed test 'D'
#   at t/04.t line 2.
# Looks like you failed 1 test of 1.
t/04.t .. Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/1 subtests 

Test Summary Report
-------------------
t/02.t (Wstat: 256 Tests: 1 Failed: 1)
  Failed test:  1
  Non-zero exit status: 1
t/04.t (Wstat: 256 Tests: 1 Failed: 1)
  Failed test:  1
  Non-zero exit status: 1
Files=2, Tests=2,  0 wallclock secs ( 0.02 usr  0.00 sys +  0.08 cusr 
+ 0.00 csys =  0.10 CPU)
Result: FAIL
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By appending t to the command line, you told prove to run all the tests in t/ together with the failed ones.

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
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