Waiting for EXE instance to close before opening another file?? (Windows)

[d0ub1ethink]

Windows version 1.5.2

I am watching a folder for PDF's, and open with SamantraPDF.

config as follows:

<logging>
    <path>C:\FileWatcher\fw.log</path>
</logging>
<watch>
    <path>C:\Users\REDACTED\Downloads\PDF</path>
    <filters>
        <files>
            <name>*.pdf</name>
        </files>
    </filters>
    <commands>       
        <command>
            <triggers>
                <trigger>Create</trigger>
            </triggers>                                     
            <path>C:\Sumantra\SumatraPDF.exe</path>                 
            <arguments>"[exactpath]"</arguments>
        </command>
    </commands>                   
</watch>    

First PDF goes into the folder, opens. Great.

Second PDF goes in, nothing happens until the first instance of the Sumantra exe is closed. If I run the two commands in a cmd prompt obviously there can be 2 instances of the exe in windows.

I do not want this waiting behavior, can I configure it to open no matter what somehow?

Thanks!