This is more of a curiosity than a problem, but in this new office I have two D-link DAP-2553's connected in a master/slave array (this just means the master keeps certain configuration options aligned with the slave). The network is set to 802.11n-only, and each AP has the same SSID and WPA2 key. The only difference is that they are on different channels (1 and 11). The WiFi network itself is working well. Users can roam around and the signal/speed is fairly consistent.
However, I notice that when I look at the 802.11 client list in the web admin page for each of the 2 APs, I see that certain clients are connected to both, for extended periods of time, but I assume they are only passing data through one of them. Not every client is seen on each AP, but at any given time the same MAC address of a WiFi adapter can be associated (and remain associated) with both APs. The client list auto-refreshes every few seconds so I believe I'm looking at the most recent rather than stale information.
One of the WiFi adapters that consistently associates with both APs is an Intel Centrino Wireless-N 1030 (laptop chip).
Is it part of the WiFi standard that more than one association per WiFi card can be established concurrently on separate APS?