Starting a DM with the same user twice results in 2 entries in m.direct.

[pixlwave]

As reported in the Element X public room, it seems that if you create a DM with someone after having left a DM with them (we don't allow creating 2 DMs with the same user), the m.direct ends up with 2 entires for that user ID. There is then a second issue at play, where if there are 2 entries for the same user ID, the SDK doesn't recognise the new DM as a direct (I haven't dug into what gets decoded).

Reported steps to reproduce:

1.	Both sides cleaned `m.direct`
2.	A starts DM with B
3.	Chat is shown as DM by EX of A and as Room in EX of B
4.	B opens EW in Browser where it is shown as DM and clicks on DM with A
5.	Chat is shown as DM in EX of B
6.	A and B leave room
7.	A starts DM with B
8.	Chat is shown as DM by EX of A and as Room in EX of B
9.	B opens EW in Browser where it is shown as DM and clicks on DM with A
10.   Chat is NOT shown as DM in EX of B

I'm not sure what is going on with 4/5 but I think the important thing here is that by 10 you have two entires in the m.direct.

We're creating DMs with the following:

let parameters = CreateRoomParameters(name: nil,
                                      topic: nil,
                                      isEncrypted: true,
                                      isDirect: true,
                                      visibility: .private,
                                      preset: .trustedPrivateChat,
                                      invite: [userID],
                                      avatar: nil,
                                      powerLevelContentOverride: .init(usersDefault: nil,
                                                                       eventsDefault: nil,
                                                                       stateDefault: nil,
                                                                       ban: nil,
                                                                       kick: nil,
                                                                       redact: nil,
                                                                       invite: nil,
                                                                       notifications: nil,
                                                                       users: [:],
                                                                       events: [
                                                                        "m.call.member": Int32(0),
                                                                        "org.matrix.msc3401.call.member": Int32(0)
                                                                       ]))
let roomID = try await client.createRoom(request: parameters)