Merge pull request #1536 from segmentio/marcus/demux

Add demux device mode warning.

Author: brennan

src/connections/destinations/add-destination.md

@@ -125,8 +125,9 @@ You can add multiple instances of a destination using the Segment Config API. Se
 ### Multi-instance destinations and Device-mode
 
 - **_Mobile_ sources cannot connect to multiple instances of a destination.**
+  - _Beware_: Bundling one instance of a destination in a mobile source while having other instances of that destination for a given source will have unexpected consequences.
 - **You can connect a source to an unlimited number of instances of a destination if all of the instances use cloud-mode.** Destinations using cloud-mode receive data directly from the Segment servers.
-- **Each source can only connect to one *device-mode* instance of a destination, in addition to unlimited cloud-mode instances.** A device-mode instance of a destination receives data directly from the user’s browser (instead of through the Segment servers), by bundling a copy of destination’s code with the Segment SDK. Segment can’t bundle multiple copies of the destination SDK and so it can’t send data to multiple instances of the destination from the browser.
+- **Non-mobile sources can only connect to one *device-mode* instance of a destination, in addition to unlimited cloud-mode instances.** A web browser device-mode instance of a destination receives data directly from the user’s browser (instead of through the Segment servers), by bundling a copy of destination’s code with the Segment SDK. Segment can’t bundle multiple copies of the destination SDK and so it can’t send data to multiple instances of the destination from the browser.
 - **You cannot connect a source to more than one instance of a destination that operates in device-mode only**. These destinations can only accept data from code directly on the user’s device, and Segment cannot include duplicates of that code for a single source.
 
 For more information see [the compatible destination lists below](#multi-instance-compatible-destinations).