Try it like this:
[{"id":"ed8c1e32.c79e28","type":"debug","z":"402f1c98.9dab44","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","x":746,"y":216,"wires":[]},{"id":"b67fdfde.581e3","type":"join","z":"402f1c98.9dab44","name":"","mode":"custom","build":"array","property":"payload","propertyType":"msg","key":"topic","joiner":"\\n","joinerType":"str","accumulate":false,"timeout":"","count":"","reduceRight":false,"reduceExp":"","reduceInit":"","reduceInitType":"num","reduceFixup":"","x":602,"y":216,"wires":[["ed8c1e32.c79e28"]]},{"id":"1d26a4f2.ef830b","type":"inject","z":"402f1c98.9dab44","name":"","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":132,"y":192,"wires":[["7114cd0e.b5e264"]]},{"id":"a6ccc9d1.76d2e","type":"inject","z":"402f1c98.9dab44","name":"","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":132,"y":252,"wires":[["e7e55a26.963b8"]]},{"id":"7114cd0e.b5e264","type":"function","z":"402f1c98.9dab44","name":"dummyarray 1","func":"msg.payload={\nvalue1: \"v1a\",\nvalue2: \"v2a\",\nvalue3: \"v3a\",\nvalue4: \"v4a\",\n};\nreturn msg;","outputs":1,"noerr":0,"x":312,"y":192,"wires":[["479fdca0.35c75c"]]},{"id":"e7e55a26.963b8","type":"function","z":"402f1c98.9dab44","name":"dummyarray 2","func":"msg.payload={\nvalue1: \"v1b\",\nvalue2: \"v2b\",\nvalue3: \"v3b\",\nvalue4: \"v4b\",\n};\nreturn msg;","outputs":1,"noerr":0,"x":312,"y":252,"wires":[["479fdca0.35c75c"]]},{"id":"479fdca0.35c75c","type":"batch","z":"402f1c98.9dab44","name":"","mode":"count","count":"2","overlap":0,"interval":10,"allowEmptySequence":false,"topics":[],"x":482,"y":216,"wires":[["b67fdfde.581e3"]]}]
Note that I have changed both objects to msg.payload (instead of msg), then use the batch node to combine them and the join node to merge them into an array of objects.
