The TigerXML versions of the Tiger corpus contain a few nodes with multiple <edge> elements for a single node. The following is a patch against version 2.2 of the Tiger corpus that removes such edges to follow the v2.1 export version of the corpus. Since the export version does not contain these edges as secondary edges, they are probably spurious.

tiger2.2singleparent.diff

--- tiger_release_aug07.corrected.16012013.xml  2013-01-16 16:35:23.000000000 +0100
+++ tiger_2.2a.xml      2013-11-03 00:02:12.890306125 +0100
@@ -3097934,7 +3097934,6 @@
       <nt id="s46234_505" cat="PP">
         <edge label="AC" idref="s46234_24" />
         <edge label="NK" idref="s46234_25" />
-        <edge label="CJ" idref="s46234_135" />
       </nt>
       <nt id="s46234_506" cat="PP">
         <edge label="AC" idref="s46234_30" />
@@ -3097951,7 +3097950,6 @@
         <edge label="CM" idref="s46234_46" />
         <edge label="AC" idref="s46234_47" />
         <edge label="NK" idref="s46234_48" />
-        <edge label="CJ" idref="s46234_133" />
       </nt>
       <nt id="s46234_509" cat="PP">
         <edge label="AC" idref="s46234_51" />
@@ -3097983,7 +3097981,6 @@
         <edge label="AC" idref="s46234_74" />
         <edge label="NK" idref="s46234_75" />
         <edge label="NK" idref="s46234_76" />
-        <edge label="CJ" idref="s46234_131" />
       </nt>
       <nt id="s46234_516" cat="NP">
         <edge label="NK" idref="s46234_82" />
@@ -3376990,22 +3376987,16 @@
       <nt id="s50224_500" cat="NP">
         <edge label="NK" idref="s50224_1" />
         <edge label="NK" idref="s50224_2" />
-        <edge label="NK" idref="s50224_133" />
-        <edge label="NK" idref="s50224_134" />
       </nt>
       <nt id="s50224_501" cat="CNP">
         <edge label="CJ" idref="s50224_7" />
         <edge label="CD" idref="s50224_8" />
         <edge label="CJ" idref="s50224_9" />
-        <edge label="AC" idref="s50224_135" />
-        <edge label="NK" idref="s50224_136" />
-        <edge label="NK" idref="s50224_137" />
       </nt>
       <nt id="s50224_502" cat="NP">
         <edge label="NK" idref="s50224_22" />
         <edge label="NK" idref="s50224_23" />
         <edge label="NK" idref="s50224_24" />
-        <edge label="NK" idref="s50224_138" />
       </nt>
       <nt id="s50224_503" cat="NP">
         <edge label="NK" idref="s50224_26" />
@@ -3377045,14 +3377036,12 @@
       <nt id="s50224_511" cat="NP">
         <edge label="NK" idref="s50224_61" />
         <edge label="NK" idref="s50224_62" />
-        <edge label="NK" idref="s50224_142" />
       </nt>
       <nt id="s50224_512" cat="CNP">
         <edge label="CJ" idref="s50224_64" />
         <edge label="CJ" idref="s50224_66" />
         <edge label="CJ" idref="s50224_68" />
         <edge label="CJ" idref="s50224_70" />
-        <edge label="NK" idref="s50224_141" />
       </nt>
       <nt id="s50224_513" cat="NP">
         <edge label="NK" idref="s50224_76" />