Add getenv() to QObjectPrivate::connectImpl() to activate logging of duplicated connections like "const bool isLogDuplicatedConnection = qgetenv("CORE_CONN_SHOW_DUPLICATED");".

The option could force a Qt::UniqueConnection type when not already set, then check as normal for existing connection - but only log a duplicated connection w/o returning - i.e. break out the "while (c2)" and continue w/ creating a new connection.

Note: Or add a new logging category for this purpose.