NO, different sticks can have different timings, different memory chips, require different voltages - if you have them - give them a try, nothing will blow up - they will either play nice or they won't
They may have different CAS timings and that, but as a general rule you can get any DDR 1066mhz and it will work fine.
As long as it is not ECC when you need non-ECC you will probably be fine. Typically only servers or very high end servers need ECC ram so.......
Chips used have different quality levels as do the boards they are built on to and the design. So you can have many different DDR3-1066 models with various levels of quality and performance.
NO, different sticks can have different timings, different memory chips, require different voltages - if you have them - give them a try, nothing will blow up - they will either play nice or they won't