I now understand it does not matter for safety reasons to transfer USDT via one or the other network.
Behind the curtains one coin can be stored on different addresses at Binance. You as user do not really have an insight in this (although you can check some historical data).

The safety of the coin itself is an aspect of how USDT works in general. USDT is (should) backed by real USD, so a failure within one network should be covered, in theory at least.
According to the "Transparency" page on Tether.to there is currently even more USDT on the Tron network than on Ethereum. So if popularity would impact risk in a positive way, this is a good thing.

Yet I highly doubt if this safety aspect applies to all crypto currencies that lives on different networks, as I wonder if all these crypto currencies have the same intricate financial/safety mechanisms.

Does Binance (or any other broker) store the same coin on different networks, when deposited via different networks?

Example:
I send 10 USDT from broker X to Binance via the Tron network
I send 10 USDT from broker Y to Binance via the Ethereum network
The balance on Binance is 20 USDT. I am able to withraw the complete amount via one or the other network is seems.

Yet where do the coins actually reside on Binance? I imagine 10 USDT on an ETH wallet and 10 on a Tron wallet?
If so, what happens if the Tron network is compromised (e.g. hack or dump), do I lose half of my funds?
As far as I know I cannot see on binance that my USDT coins are devided amongst different addresses/networks.