From @FROGGS

~/dev/MoarVM$ cat foo.pm
say 42

~/dev/MoarVM$ cat bar.pm
use foo;

~/dev/MoarVM$ cat baz.pm
use foo;

~/dev/MoarVM$ perl6-p -I. -e 'use bar; use baz;'
42

~/dev/MoarVM$ perl6-j -I. -e 'use bar; use baz;'
42
===SORRY!===
SC with handle 6D7A41759C6E80568D34201B72788AD6F9AFBF10 already exists

~/dev/MoarVM$ gdb --args /home/froggs/dev/nqp/install/bin/moar --libpath="/home/froggs/dev/nqp/install/languages/nqp/lib" --libpath="/home/froggs/dev/nqp/install/languages/perl6/lib" --libpath="/home/froggs/dev/nqp/install/languages/perl6/runtime" /home/froggs/dev/nqp/install/languages/perl6/runtime/perl6.moarvm -I. -e 'use bar; use baz;'
GNU gdb (GDB) 7.6.1-ubuntu
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+​: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software​: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
For bug reporting instructions, please see​:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /home/froggs/dev/nqp/install/bin/moar...done.
(gdb) run
Starting program​: /home/froggs/dev/nqp/install/bin/moar --libpath=/home/froggs/dev/nqp/install/languages/nqp/lib --libpath=/home/froggs/dev/nqp/install/languages/perl6/lib --libpath=/home/froggs/dev/nqp/install/languages/perl6/runtime /home/froggs/dev/nqp/install/languages/perl6/runtime/perl6.moarvm -I. -e use\ bar\;\ use\ baz\;
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
42

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7a075a4 in gc_free (tc=0x603430, obj=0x7ffff670f890) at src/6model/reprs/SCRef.c​:82
82 HASH_DELETE(hash_handle, tc->instance->sc_weakhash, sc->body);
(gdb) bt full
#​0 0x00007ffff7a075a4 in gc_free (tc=0x603430, obj=0x7ffff670f890) at src/6model/reprs/SCRef.c​:82
  _hd_bkt = <optimized out>
  _hd_hh_del = <optimized out>
  sc = 0x7ffff670f890
#​1 0x00007ffff79f6106 in MVM_gc_collect_free_nursery_uncopied (tc=tc@​entry=0x603430, limit=0x7ffff67f9fe8) at src/gc/collect.c​:533
  obj = 0x7ffff670f890
  item = 0x7ffff670f890
  dead = <optimized out>
  scan = 0x7ffff670f890
#​2 0x00007ffff79f02fe in run_gc (tc=tc@​entry=0x603430, what_to_do=what_to_do@​entry=0 '\000') at src/gc/orchestrate.c​:291
  other = 0x603430
  thread_obj = <optimized out>
  gen = 0 '\000'
  i = <optimized out>
  n = <optimized out>
#​3 0x00007ffff79f06fe in MVM_gc_enter_from_allocator (tc=tc@​entry=0x603430) at src/gc/orchestrate.c​:367
  last_starter = 0x33144d0
  num_threads = 0
#​4 0x00007ffff79f07e7 in MVM_gc_allocate_nursery (tc=tc@​entry=0x603430, size=48) at src/gc/allocation.c​:32
  allocated = 0x0
#​5 0x00007ffff79f0825 in MVM_gc_allocate_zeroed (tc=tc@​entry=0x603430, size=<optimized out>) at src/gc/allocation.c​:49
No locals.
#​6 0x00007ffff79f0976 in MVM_gc_allocate_object (tc=0x603430, st=0x119dbc0) at src/gc/allocation.c​:85
  obj = <optimized out>
#​7 0x00007ffff7a00a76 in allocate (tc=<optimized out>, st=<optimized out>) at src/6model/reprs/P6opaque.c​:111
No locals.
#​8 0x00007ffff79d1fa9 in MVM_interp_run (tc=tc@​entry=0x603430, initial_invoke=initial_invoke@​entry=0x7ffff7a251e2 <toplevel_initial_invoke>,
  invoke_data=<optimized out>) at src/core/interp.c​:1981
  type = <optimized out>
  obj = <optimized out>
  op = <optimized out>
  cur_op = 0x7ffff57332cc "%"
  bytecode_start = 0x7ffff57331b0 "\237"
  reg_base = 0x48453c0
  cu = 0x709370
  cur_callsite = 0x2a598a0
#​9 0x00007ffff7a2588b in MVM_vm_run_file (instance=instance@​entry=0x603010, filename=<optimized out>) at src/moar.c​:176
  start_frame = <optimized out>
  tc = 0x603430
  cu = 0x7ffff63fa6a0
#​10 0x0000000000400ceb in main (argc=8, argv=0x7fffffffdda8) at src/main.c​:146
  instance = 0x603010
  input_file = <optimized out>
  lib_path = {0x7fffffffe182 "/home/froggs/dev/nqp/install/languages/nqp/lib", 0x7fffffffe1bb "/home/froggs/dev/nqp/install/languages/perl6/lib",
  0x7fffffffe1f6 "/home/froggs/dev/nqp/install/languages/perl6/runtime", 0x0, 0xf0b2ff "@​", 0xc2 <Address 0xc2 out of bounds>, 0x1 <Address 0x1 out of bounds>,
  0x400d6d <__libc_csu_init+93> "H\203\303\001H9\353u\352H\213\\$\bH\213l$\020L\213d$\030L\213l$ L\213t$(L\213|$0H\203\304\070\303\017\037\200"}
  dump = 0
  argi = <optimized out>
  lib_path_i = 3

From @FROGGS

Fixed on moar​: MoarVM/MoarVM@068ce44

Issue still there on jvm bakend.

From @FROGGS

Fixed for jvm in Raku/nqp@6d4ea16d95
Test​: https://rt-archive.perl.org/perl6//Public/Bug/Display.html?id=121253

@FROGGS - Status changed from 'open' to 'resolved'