It may be best to go back to my first suggestion which is to disconnect the Samsung drive and install/partition with only the Seagate connected.
Disconnecting the HDD is not difficult. There are two connectors: one wide flat cable for data and one 4-pin connector for power. Use common sense when pulling them out.
Disconnect your computer from the power source completely before you delve inside the CPU. Don't just turn it off. Pull out the mains plugs (including that of the monitor and anything else directly connected to the CPU) from the mains or UPS.
Discharge your body of any possible static electricity by momentarily touching a grounded metal object such as a water tap or pipe.
You may have to apply some force while pulling out the 4-pin Molex connector from the HDD. If necessary, wiggle it from side to side, not up and down.
For the flat data cable, don't pull by the wire alone. Grasp as much of the connector as you can as well. The individual wires and the plastic bar clamping them to the connector are rather delicate. You may have to wiggle it a bit too.
That's all there is to it. Don't let the precautionary warnings scare you off

Just use your common sense.
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I have to turn in "early" tonight. We can take it up again tomorrow. You can email me if you like at pjdd (at) rediffmail (dot) com