It's all about the Software

Ah - THAT one replies with a sane value for the tuner:
22:25:29.646: Radio RTL SDR (USB): Connect> Tuner .........: Rafael Micro R820T
I suspect your other dongle is a fitipower dongle that has had its id information modified. Let's work on that dongle to make a functioning configuration that can be easily distinguished from the other dongle. That means changing the serial number.

With only that dongle plugged in let's change it's serial number. On the home menu you should find "Radio Configuration". Select that. In the dialog that comes up select "EEPROM".

** Oops - Ah Simon, what is the "load" button supposed to do? **

Well, the "Default" button seems to read what is already in the dongle. So you can select "Default" and then on the third line change the "serial number". That can, literally, be a sequence of any 8 bit characters as you want - no unicode even though it's saved internally as unicode. Go figure. For example I have one named "15" and another "RTLSDR 2". Keep it fairly short. 20 characters is safe. 80 might not be.

At this point you may need to redo the definition process for it. But that's easy.

After that both dongles should be safe in the system, which is a good start. Then we can study what you are seeing with tuning not changing. Do remember there are two aspects to tune, the front end frequency, which is the center frequency of the display. The second is the receiver frequency. Changing the center frequency rather wildly will not change the receiver frequency. If you move the center far enough that the receiver frequency is out of band the audio mutes. If that description clears up your problem I for one will be happy. It would rule out something really weird.

====== for Simon
On this dialog: I get this error when I press "Load".
On the other hand I have confirmed that the "Default" button does read the dongle contents for editing.

{^_^}

the load button say EEPROM not found
the Default button fill out the lines butt I cannot change anything, its gray out the save button work's

I never use both dongles at the same time i try it once and did not work so...

Pirpy, I've directed Simon to my message above as we've found a buglette that should be repaired.
Meantime, it looks like SDRC may be doing the logical thing, not changing receiver frequencies when the front end frequency is changed. The receiver spectrum would go flat and audio would stop; but, the receiver tuning would remain unchanged.

If your computer has enough processing power running a pair of rtlsdr type dongles is no big strain. It would require two different instances of SDRC or SDRC plus something like SDRSharp.

{^_^}

Simon is working on it. This may be due to a change in SDRC from "way back" so it may take us a little time to deal with. I'm going to gather up tools and try to help him. (I have an sdr rtlsdr source dll separate from his. And it shows the same problem. Since I have source code I can follow the debugging through the code and see where and why it broke.)

{^_^}

Ah - here we have a version that should work. (It worked for me.) Click on the private message button at the top of this page and pick up the private message I am sending with the link to the build. (It is a test build, the very latest build of SDRC.)

{^_^}

No personal message from you ?, please send again.

Best Regards

Borut

Sent again. I checked and it shows in the outbox this time. The preceding one didn't make it for some reason, maybe me fmubling (sic) a button.

{^_^}

So I can change the serial number in eeprom but both radios are stil not working together, in radio definitions is still only serial number *001 found
and the frequency tunning still does not work.
latest log

this is rtl-sdr.com with changed serial to *0003, but in log the working adress is stil serial *0001