UART devices: Baud rates different by a factor
Serial data is just a series of 1's and 0's on the wire so it is possible to synthetically make one data stream out of the bits of another by mimicking bit patterns...

https://wp.josh.com/2014/09/03/inside-neouart-tricking-a-serial-port-into-being-a-signal-generator/

But it is usually not as simple as just doubling the sender's baud rate and sending each data bit twice because there usually other bits in the stream besides the data bits like the start, stop, and parity bits. 



It is often possible to work around these limitations, but the strategies are specific to your sending hardware (can you change the bits? the framing? the parity? on the fly?) and you application (can you live with not being able to send some data values and instead changing them to nearby values that fit into the allowed patterns?).

If you give more info on your hardware and protocol we can better help brainstorm ideas to get there!