Resolves: tdf#121520 duplicate languages in dropdown

Change-Id: I5bbde305bf06ac1f754f24eb93e89cb3d9cf6058
Reviewed-on: https://gerrit.libreoffice.org/64869
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>
diff --git a/svx/source/dialog/langbox.cxx b/svx/source/dialog/langbox.cxx
index 69d1ab3..fedbe1a 100644
--- a/svx/source/dialog/langbox.cxx
+++ b/svx/source/dialog/langbox.cxx
@@ -551,12 +551,15 @@ void LanguageBox::AddLanguages(const std::vector< LanguageType >& rLanguageTypes
            if (lcl_isScriptTypeRequested( nLang, nLangList))
            {
                int nAt = ImplTypeToPos(nLang);
                if (nAt == -1)
                {
                    rEntries.push_back(BuildEntry(nLang));
                    if (rEntries.back().sString.isEmpty())
                        rEntries.pop_back();
                }
                if (nAt != -1)
                    continue;
                weld::ComboBoxEntry aNewEntry(BuildEntry(nLang));
                if (aNewEntry.sString.isEmpty())
                    continue;
                if (std::find_if(rEntries.begin(), rEntries.end(),
                                 [=](const weld::ComboBoxEntry& rEntry){ return rEntry.sId == aNewEntry.sId; }) != rEntries.end())
                    continue;
                rEntries.push_back(aNewEntry);
            }
        }
    }