salva@atun:/tmp/unicode$ re.pl
$ $a="a\xf1o"
a�o
$ $b = $a
a�o
$ use Devel::Peek

$ utf8::upgrade($b)
4
$ Dump $a
SV = PV(0x557576d4e2d0) at 0x557576812a80
  REFCNT = 1
  FLAGS = (POK,IsCOW,pPOK)
  PV = 0x557576d516c0 "a\361o"\0
  CUR = 3
  LEN = 10
  COW_REFCNT = 0

$ Dump $b
SV = PV(0x557576d4e2a0) at 0x557576d4b7d0
  REFCNT = 1
  FLAGS = (POK,pPOK,UTF8)
  PV = 0x557576d6e6e0 "a\303\261o"\0 [UTF8 "a\x{f1}o"]
  CUR = 4
  LEN = 10

$ open A, ">$a";
1
$ open B, ">$b";
1
$ system "ls"
aņo  a?o
0
$ $a eq $b
1