Hi, can I ask a very Beginner Question? Here is the Situation:
I have an RC522 RFID reader that contains a pin named RST, and I have an RTC DS1302 that contains a pin named also RST, can I put both pins on the same pin in esp 32? the same question goes for CLK pins! can i put both of them on the same esp32 pin?
I want to also of CLK pin of 4-digits 7 segment I have 2 of them can i put both CLK pins together?
Depends on the detailed specs. post links to the hardware and we can better judge.
Things SDA/SCL can be ganged as can MOSO/MISO. But both are separate.
Without researching the chips, probably yes. As long as both RST pins are active low, which is the normal mode, and the RST line has a 10K pullup then a low on RST should reset both chips.
Also, if either of the chips need to reset for every read, then you may have a conflict.
CLK is more likely a bus. I have put multiple displays on the same SDA and SCL lines.
Breadboard it. The worst that can happen is it won't work.
No, worst case is that the magic smoke escapes! LOL
Unlikely since RST and CLK are both inputs.
was thinking more about reversing vcc & gnd when breadboarding ... not like something like that has ever happened in my lab!
Maybe... These are both inputs, right? They are usually wired to a reset button?
If they are both the same voltage (I think the ESP32 is a 3.3V device) and if they are both the same "logic" (i.e. If low or ground triggers a reset on both devices and under normal non-reset conditions are high).
Yes. It's OK to connect (or "short") two inputs together, but you should never connect/short two outputs together because one can be writing high while the other is writing low and they will "fight" and something can burn-up.
...It's sort-of like you can have many people listening but only one person talking. Except with more than one person talking nothing burns-up. 
And most digital outputs can't "turn-off" so they are always writing high or low.
No. The RTC module needs three dedicated pins.
The LED display & RF modules use SDA/SCL pins and CAN be bussed.
i use that exact clock module and it is NOT SDA/SCL.
Hello sakaturi
Keep it simple and stupid.
Run some tutorials to the hardware selected.
If you are happy with the results of the tutorials you can merge these to your project.
Have a nice day and enjoy coding in C++.
Дайте миру шанс!
Oooh, I don't know if that is guaranteed. 
Why do you imagine the MFRC522 requires a reset? The DS1302 certainly should not. 
