'Device or resource busy' error thrown when trying to record audio using arecord

I’m trying to record audio that is being played on separate channels using arecord. I do this by executing the following command in separate threads in a python script:

arecord -D plug:"+str(in_id)+" -c 1 -d "+str(duration)+" -f S16_LE -r "+str(rate)+" "+rec_filename

where in_id is the input channel variable that I pass to each of the threads. But then, the following error is thrown:

ALSA lib pcm_dsnoop.c:606:(snd_pcm_dsnoop_open) unable to open slave
arecord: main:722: audio open error: Device or resource busy

When I run lsof /dev/snd/pcm* right before I start recording using arecord in my record function in the program, I see the following:

COMMAND   PID        USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
aplay   12236       user4  mem    CHR  116,3           493 /dev/snd/pcmC1D0p
aplay   12236       user4    4u   CHR  116,3      0t0  493 /dev/snd/pcmC1D0p

My device definition for input channels in .asoundrc is as follows:

pcm.!default {
    type plug
    slave {
       pcm "hw:1,0"
    }
}

ctl.!default { 
    type hw
    card 1
}

pcm_slave.usb_audio_1 {
    pcm "hw:1,0"
    channels 8
    rate 44100
    buffer_size 4096
    period_size 1024
}

pcm.outch<num> {
    type dshare
    ipc_key <id>
    slave usb_audio_1
    bindings [ <ch_num> ]
    hint.description "USB output/playback channel <num> (from output port <num>)"
}

pcm.inch<num> {
    type dsnoop
    ipc_key <id>
    slave usb_audio_1
    bindings [ <ch_num> ]
    hint.description "USB input/capture channel <num> (from input port <num>)"
}

where <num> takes all values between 1 and 8 and <ch_num> takes all values between 0 and 7.

Since, the error clearly says there is a definite problem with dsnoop, does that mean that it is not meant for simultaneous/multi-channel recording? I mean is there a conflict between dsnoop and dshare or if dsnoop can record/capture from only one channel at a time? Is there another way I can achieve this?