Not only as NetWallah points out are perl variables case-sensitive, i.e. $splice is different from $Splice, but you need to manipulate your newly created slide inside the while/for loop:

$pname = "...";
for my $i (0..4) {
  $slide = $ppt->Slides->Add(...);
  $slide->Shapes->AddOLEObject(...);
}
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