my @randUnique = shuffle map{ 
    sprintf "%07d%05d", 1e7+int( rand 1e6 ), $_ 
} 1 .. 25e3;;

print $randUnique[ $_ ] for 1 .. 10;;
1091497817847
1018472205890
1028707802676
1078720009752
1016540524132
1074148507607
1022293016846
1018341020021
1038845808717
1056634512933