how do you monitor two ups backup device at once since powerchate is window

Do you mean you have two Macs connected to a single UPS and need both to monitor the state of power? This is the more usual requirement.

If so then in theory APC provide a command line tool to allow the Macs to use a network connection to talke to the APC UPS. (It is not possible to connect two computers via USB to a single UPS.)

Personally I regard APC's Mac software as so bad I would not install it. There is however another approach, there is free open-source software called 'NUTS' which stands for Network Ups ToolS. With this either both computers can again talk to the UPS over the network, or more interestingly one can be directly connected via a serial connection or USB and then act as a 'server' with additional computers asking it what the status is.

This works great, almost certainly better than APC's own grotty software. 😉

See http://www.networkupstools.org

Sadly NUTS for Mac is still command line only but I trust their software more than I would APC's own.

If you want to monitor two different physical UPS devices e.g. in a server room(s), then for a Mac your best best is going to be to use an SNMP console of some sort and use SNMP calls to talk to the network interface of the UPS devices. Of course this requires the UPS devices to have network interface which in general the bigger models do.