You may try something like (here simulating your sources from videotestsrc):
gst-launch-1.0 -e \
videotestsrc ! video/x-raw, width=1920, height=1080, framerate=30/1 ! tee name=t1 \
t1. ! queue ! video/x-raw, width=1920, height=1080, framerate=30/1 ! nvvidconv ! nvv4l2h264enc maxperf-enable=1 bitrate=4000000 profile=4 ! h264parse ! queue ! mux. \
pulsesrc ! audio/x-raw,width=16,depth=16,rate=44100,channel=1 ! audioconvert ! voaacenc ! aacparse ! queue ! mpegtsmux name=mux ! filesink location=feed1mp1080HW1.ts \
t1. ! queue ! nvvidconv ! "video/x-raw(memory:NVMM),width=959,height=540,framerate=30/1,format=NV12" ! nvoverlaysink overlay-x=0 overlay-y=270 overlay-w=959 overlay-h=540 overlay=1 \
videotestsrc ! nvvidconv ! "video/x-raw(memory:NVMM),format=I420,width=1920,height=1080,framerate=30/1" ! nvjpegenc ! image/jpeg,width=1920,height=1080,framerate=30/1 ! jpegparse ! tee name=t2 \
t2. ! queue ! nvv4l2decoder mjpeg=1 ! nvvidconv ! "video/x-raw(memory:NVMM,format=I420" ! nvv4l2h264enc maxperf-enable=1 bitrate=4000000 profile=4 ! h264parse ! mpegtsmux ! filesink location=feed2mp1080HW1.mp4 \
t2. ! queue ! nvv4l2decoder mjpeg=1 ! nvvidconv ! "video/x-raw(memory:NVMM),framerate=30/1,format=NV12,width=960,height=540" ! nvoverlaysink overlay-x=960 overlay-y=270 overlay-w=960 overlay-h=540 overlay=2
[EDIT: Without I420 conversion between MJPEG decoder and H264 encoder, it generates repeated kernel message:
host1x 13e10000.host1x: nvhost_syncpt_wait_timeout: invalid syncpoint id 0
]