[BUG] Incorrect "Duplicate qubit argument"

[Sola85]

Environment

• PyQASM version: main as of today
• Python version: 3.11.5
• Operating system: Linux 1be07c5250d0 5.15.153.1-microsoft-standard-WSL2 # 1 SMP Fri Mar 29 23:14:13 UTC 2024 x86_64 GNU/Linux

What happened?

Currently, broadcasting of multi-qubit gates works like e.g. cx a, b, c, d; -> cx a, b; cx c, d;.

This means that cx q[0], q[1], q[1], q[2]; should be fine in principle as this should simply translate to cx q[0], q[1]; cx q[1], q[2];.

But instead compiling this results in
pyqasm.exceptions.ValidationError: Duplicate qubit q[1] argument

Suggestions (Optional)

To fix this, the check for duplicate arguments should only happen after the broadcast qubits have been unrolled.

But this issue is probably not of high priority since I don't know how many people actually use qubit broadcasting on multi-qubit gates.